257 Free Online Tools
QR codes, image conversion, video processing, text utilities — no signup, no watermarks.
QR Code (6 tools)
QR Code Generator
Convert URLs, Wi-Fi credentials, vCards, and text to QR codes. Download as watermark-free PNG/SVG, free forever, no signup required.
Wi-Fi QR
Turn Wi-Fi name and password into a QR code so guests can connect with a single scan. Perfect for cafes, restaurants, and Airbnb hosts.
vCard QR
Encode name, company, phone, and email into a QR code. Scan to save the contact instantly — print on paper business cards for one-second exchanges.
QR Code Reader
Upload an image containing a QR code and it's decoded automatically. Works with Wi-Fi, URL, and vCard QRs. Use it on a PC without a camera.
QR with Logo
Insert a logo or icon into the center of a QR code — great for branded QRs. Error correction level auto-adjusts. Useful for café/shop logo QRs, business cards, event posters, brochures, and wedding invitations.
QR with Text
Insert text (shop name, person's name, event title, brand) in the center of a QR code, with free color and background shape options. Use it instead of a logo image for store signage, business cards, event posters, or labeling a Wi-Fi QR with the network name.
Image (38 tools)
Background Remover
Automatically remove the background from photos of people or objects and save as a transparent PNG. The AI model runs entirely in your browser — your photos are never uploaded. Great for profile photo cutouts, product photos, ID photos, sticker making, and compositing.
Aspect Ratio Calculator
Keep an aspect ratio (e.g. 16:9) and enter just the width or height — the other is calculated automatically. Useful for matching video resolutions, thumbnail/banner sizes, image resizing, and monitor/design work. Also reverse-calculates the ratio from two dimensions.
Color Blindness Simulator
Simulate how an image or color appears to people with color vision deficiencies — protanopia (red-blind), deuteranopia (green-blind), tritanopia (blue-blind), and achromatopsia. Useful for web/app accessibility checks, contrast verification, and infographic/chart color choices. Processed in your browser.
PNG → JPG
Instantly convert PNG images to JPG. Processing happens entirely in your browser — files are never uploaded. Adjustable quality, free, no signup.
JPG → PNG
Convert JPG images to PNG. PNG is lossless, ideal for print and editing. Processing happens safely in your browser.
WebP → JPG
Convert WebP images to JPG. Solves compatibility issues when attaching to messengers or documents that don't support WebP.
JPG → WebP
Convert JPG to WebP to reduce file size by 30–70%. Faster page loading and better SEO scores.
Image Compress
Shrink photo file sizes by 80%+ with minimal quality loss. Perfect for email attachments, forum uploads, and messenger sharing.
Image Resize
Resize images to any pixel dimensions. Auto-keeps aspect ratio, preserves quality, free, no watermark.
Image OCR
Extract text from images using Tesseract.js with Korean model support. Digitize receipts, book pages, screenshots, business cards, and more.
YouTube Thumbnail DL
Enter a YouTube video URL or ID to download the auto-generated thumbnail in 5 resolutions (max / standard / high / medium / default).
Color Palette Generator
Generate 5-color palettes by harmony rule — monochrome, analogous, complementary, triadic, tetradic. Click to copy HEX.
OG Card Maker
Generate social-share OG images (1200×630), Instagram squares/vertical, YouTube thumbnails. Title, subtitle, tag, color presets — instant PNG.
Image Batch Editor
Compress, resize, and format-convert (JPG/PNG/WebP) multiple images at once. ZIP download. For blogs, e-commerce product photos, album backups.
Favicon Generator
Create a complete favicon bundle from a single image. Get 16/32/48/64/128/256 PNGs and ICO file as one ZIP.
Image Filter
Apply grayscale, sepia, blur, brightness, contrast, and saturation filters to photos. Real-time preview, minimal quality loss, all in your browser.
Image Pixelate/Mosaic
Apply mosaic to a whole image or selected area to hide faces, license plates, or sensitive info. Adjustable pixel size.
Image Stack
Combine multiple images into one. Choose horizontal stack, vertical stack, or grid layout. Adjustable spacing and background color.
Image Border
Add a colored border to a photo. Adjustable thickness, color, and rounded corners. Great for Polaroid-style SNS posts.
EXIF Viewer
Check metadata of JPG/HEIC photos. Camera model, capture time, GPS coordinates, ISO, shutter, aperture, lens, and more — all at a glance.
Color Extract
Auto-extract main colors from a photo to create a palette. Great for design inspiration and brand color analysis.
Image Text Overlay
Add titles or captions to photos instantly. Adjustable font, color, size, outline, and position. Perfect for thumbnails, quote graphics, and notice images.
Image → ASCII
Convert photos to ASCII art using characters. Adjustable width, invert option, and character sets. Copy as text or save as PNG.
HEIC → JPG
Convert .heic photos from iPhone to .jpg that displays everywhere. Solves messenger, document, and older Windows compatibility issues at once. Useful for attaching to reports, sending to a print shop, sharing photos with Android friends, and inserting into Word or Hancom Office documents.
EXIF Remove
Wipe location (GPS), capture time, and device info from your photos. Recommended for protecting privacy before posting to Instagram, Twitter, or Karrot (Korean local marketplace), before publishing review photos to a blog, or when sharing photos with strangers.
Image Crop
Crop a photo to the area you want. Supports 1:1, 4:3, 16:9, 9:16 fixed ratios or free crop. Great for square profile pics, Instagram Stories at 9:16, YouTube thumbnails at 16:9, card-news at 4:5, and other SNS size requirements.
Image Rotate
Rotate photos 90/180/270 degrees or flip horizontally/vertically. Perfect for straightening sideways photos, matching scan orientation, or fixing badly-taken pictures. Pixels are rotated as-is without quality loss.
Text Card Maker
Turn quotes, notices, or sayings into SNS-shareable image cards and save as PNG. Gradient background with adjustable font and size. Useful for Instagram card news, Twitter-quote-style posts, store menus/notices, and study note summaries.
Image Compare Slider
Create a slider preview comparing two images. Great for before/after retouching, interior renovation, diet progress, A/B design comparisons, and time-lapse pairs of the same location.
Image ZIP
Bundle multiple images into one ZIP file. Handy for email attachments, KakaoTalk sharing, cloud uploads, external disk backups, and shipping report attachments in one go.
Image Invert
Invert image colors to create a negative effect. Recreate old film photos, prepare images for dark mode, invert black-and-white diagrams, or experiment with design concepts.
Image Watermark
Overlay a logo or image as a watermark on a photo. Adjustable position, opacity, and size. Useful for photographer copyright marks, preventing image theft on blogs/SNS, company logos, and source credit on lecture materials.
Color → Transparent
Make a specific color (usually white background) transparent in an image. Useful for removing white backgrounds from logos, cleaning up signature/stamp scans, extracting icons, or making transparent images for slides.
RGB Channels
Separate an image's red, green, and blue channels into grayscale images. Useful for photo compositing, color analysis, digital forensics, print separation preview, and design learning.
Image Free Rotate
Rotate images freely in 1° increments. Useful for straightening crooked photos. Great for fixing tilted phone shots, straightening skewed document scans, design effects, and rotated business card or invitation designs.
KakaoTalk Chat Screenshot
Create KakaoTalk-style fake chat screenshots and download as PNG. For blog reviews, fiction, humor, scenario examples, or ad mockups. Customize the room name, other person's name, individual messages, and times. Visually mimics KakaoTalk bubble design.
Meme Generator
Upload an image and add top/bottom text to create classic memes. Adjust font size, color, and outline. Download as PNG. For SNS sharing, chat reactions, YouTube thumbnails, and blog humor posts.
Image Color Picker
Upload an image and click any point to get that pixel's HEX/RGB/HSL color. Great for design color matching, brand color extraction, identifying specific colors in photos, and unifying PPT/poster palettes.
Barcode (9 tools)
Barcode Generator
Generate all major 1D barcodes — Code 128, EAN-13, EAN-8, UPC-A, Code 39, ITF-14, Codabar — in one place. Download as PNG/SVG, customize colors, toggle text. Useful for retail price tags, library labels, asset tracking, shipping invoices, pharmacy management, and student IDs.
Barcode Reader
Automatically decode almost any barcode from images — EAN-13, Code 128, Code 39, UPC, ITF, QR, DataMatrix, PDF417, and more. Decode without a camera right in your PC; photos are processed in the browser and never uploaded. Useful for checking product photos, verifying printed labels, extracting ISBNs from book photos, and analyzing receipts.
EAN-13 Barcode
Generate EAN-13 barcodes — the global retail product barcode standard (Korea uses prefix 880). For store price tags, self-made product labels, small-business POS systems, and warehouse labels. The check digit is auto-calculated: enter 12 digits and the 13th is added.
EAN-8 Barcode
Compact EAN-8 barcodes for small items where a full EAN-13 label won't fit — lip balms, candy, small parts. Enter 7 digits and the check digit is auto-added.
UPC-A Barcode
US/Canada retail product barcode standard. 12 digits (manufacturer + product + check). Required for US retail, Amazon FBA, and US-bound exports. Korean products sold in the US often need UPC-A instead of EAN-13.
ISBN Barcode
Enter ISBN-10 or ISBN-13 to generate the EAN-13 barcode. ISBN-10 is automatically converted to ISBN-13 with the 978 prefix. Use it for book covers, library cataloging, publication registration, and independent author cover design.
Code 128 Barcode
The most popular barcode for logistics, shipping, and asset management. Code 128 supports all ASCII characters (letters, digits, symbols) and packs more data into the same width than older formats. Great for tracking numbers, asset tags, student IDs, and serial numbers.
Code 39 Barcode
Code 39 (since 1974) is the most universally supported 1D barcode — almost every scanner reads it. Supports uppercase letters, digits, and a few symbols (-, ., space, $, /, +, %). Common in legacy industrial, government, school, and library systems. Good for asset labels, student IDs, and government forms.
ITF-14 Barcode
ITF-14 barcodes for shipping cartons / outer packaging. Enter 13 digits — the 14th check digit is auto-added. ITF-14 has thick bars and large print so it scans from a distance — the standard for outer cartons in warehouses, on trucks, and on shipping pallets.
Video (17 tools)
Video → GIF
Convert MP4, MOV, WebM videos to animated GIFs. Adjustable FPS, size, and length. Files are processed in your browser and never uploaded.
Video → MP3
Extract audio from videos like MP4 and save as MP3. Useful for lectures, interviews, and music videos. Processing happens in your browser.
Video Compress
Reduce video file size by 50–80% with minimal quality loss. Solves upload size limits on messengers, email, and forums.
Video Trim
Cut out the section of a video you want. Set start and end points with sliders. Lossless fast cutting (stream copy method).
Subtitle SRT/VTT Editor
Convert between SRT and VTT subtitle files and shift timing by an offset to fix sync. Extract plain text too.
Video Editor (All-in-One)
Trim, rotate, flip, change speed, mute, resize, and compress in a single tool. Combine multiple edits in one ffmpeg.wasm pass to minimize quality loss.
GIF → MP4
Convert animated GIFs to MP4 video. File size typically drops 70–90% with universal platform compatibility. Useful for autoplaying MP4 instead of GIF on blogs and webpages, when GIFs won't send through KakaoTalk, and for posting light videos to Twitter/X instead of heavy GIFs.
Video Rotate
Straighten sideways videos or flip them horizontally/vertically. Based on ffmpeg.wasm, with audio kept intact. Useful for fixing videos shot vertically but saved sideways, creating mirror effects, and batch-fixing videos with bad rotation metadata.
Video Thumbnail
Save a still frame from any video moment as PNG. Useful for making YouTube thumbnails, capturing lecture slides, citing movies or news clips, and pulling SNS preview images.
Video Speed
Slow down or speed up video playback. Useful for fast-listening to lectures at 1.5–2x, slow-motion analysis of golf swings and workouts, compressing cooking videos, and breaking down dance choreography. Based on ffmpeg.wasm.
Audio Trim
Cut a segment from MP3, WAV, M4A, OGG, and other audio files. Fast lossless cutting via ffmpeg.wasm. Great for grabbing a chorus, pulling quotes from lectures or podcasts, making ringtones and alarms, and keeping only the key part of a meeting recording.
Video Merge
Join multiple videos in sequence into one file. Powered by ffmpeg.wasm — same codec recommended. Useful for combining clips you split while filming on a phone, joining lecture series, or building wedding highlight reels.
Video Mute
Completely remove sound from a video. ffmpeg copies only the video stream — fast, with no quality loss. Useful for removing noisy backgrounds, stripping copyrighted music, and creating silent video clips for SNS or GIFs.
Video Info
Show a video's resolution, length, file size, duration, and basic info. Useful for checking specs before upload, prepping for edits, verifying SNS attachment limits, and deciding which tool to use.
Video Resize
Convert videos to 360p, 720p, 1080p, or 4K. Useful for reducing 4K to 720p for KakaoTalk attachments, making mobile-friendly versions, and shrinking lecture videos for data savings.
Audio Merge
Join multiple audio files in order into one. Useful for combining multi-session lecture recordings, music medleys, podcast intro/main/outro bundles, and split meeting recordings.
Audio Volume
Boost or lower audio in decibel (dB) units. Useful for raising too-quiet lecture recordings, lowering loud mic input, and matching volume across multiple audio files.
Korean HWP (6 tools)
HWP Viewer
Open .hwp and .hwpx files directly in your browser — no Hancom Office required. Page navigation and zoom supported. Files never leave your device.
HWP → Text
Extract body text from Korean HWP documents as .txt. Useful for pasting into messengers, email, or translators. Safe browser-based processing.
HWP → PDF
Convert Korean HWP documents to PDF instantly — no Hancom Office needed. Perfect for sharing or printing.
HWP → HWPX
Convert legacy .hwp files to the Korean government standard .hwpx format (KS X 6101). Useful for public-sector submissions and modern tool compatibility.
HWPX Editor
Write text and pick a font and size, then save as a Korean-standard HWPX file (KS X 6101) — no Hancom Office required. Useful on machines without a Hancom license.
Word (DOCX) Viewer
Open Microsoft Word .docx files in your browser without Word. Extract text only or save as .txt.
Calculator · Life (53 tools)
Korean Car Tax
Compute annual Korean car tax and local education tax from engine displacement and vehicle age. Supports sedans, business vehicles, hybrids, and EVs.
Severance Pay Calculator
Estimate Korean statutory severance pay from tenure, average wage, bonus, and unused leave. Useful before resignation, retirement, or comparing DB vs DC pension schemes.
Korean Income Tax
Estimate Korean comprehensive income tax from gross income, expenses, and deductions. For May tax-filing season self-checks, freelance/rental income estimates.
Real Estate Tax (KR)
Compute Korean acquisition, transfer, and property taxes — single vs multi-home, holding period, capital gain progressive rates, and standard-value property tax.
Pomodoro Timer
25-min focus + 5-min break cycles for productivity. Long break every 4 cycles, sound + browser notifications, cycle statistics.
Trip Cost Split
Split travel or dining expenses among members with minimum-transfer settlement. Per-expense partial sharing, greedy optimization.
Loan Calculator
Compute monthly payment and total interest under three Korean repayment methods: equal payment (원리금균등), equal principal (원금균등), and bullet (만기일시상환). Useful for mortgage (LTV) simulations, Jeonse loans, credit loans, and car installment comparisons.
Savings · Deposit Calculator
Calculate maturity for Korean installment savings (적금) and term deposits (예금) under simple or compound interest. Auto-deducts 15.4% interest tax with a tax-free option. Useful for comparing Youth Leap Account, ISA, and regular savings, simulating bank products, and planning lump-sum goals.
Net Salary (Korea)
From your gross annual salary, deduct national pension, health insurance, employment insurance, income tax, and local tax to get monthly take-home pay. Supports dependents, children, and non-taxable items. Useful for offer evaluation, job-change comparisons, budgeting, and negotiation prep (2026 rates).
GPA Calculator
Enter courses, grades, and credits to compute GPA, with conversions across 4.5, 4.3, 4.0, and 100-point scales. Handles P/NP and retakes. Useful for end-of-semester self-check, US grad school applications, and scholarship prep.
Pyeong ↔ m² Converter
Convert precisely between Korean pyeong (평, traditional area unit) and square meters. Includes presets for common apartment sizes and an exclusive-use area estimate. Useful for property listings, moving comparisons, furniture planning, and interior quotes.
Graphing Calculator
Plot y = f(x) functions interactively on a 2D canvas. Multiple functions with colors, drag to pan, scroll to zoom, and live cursor coordinates.
Formula Builder (Buttons)
Build math formulas by clicking buttons — fractions, radicals, integrals, sums, matrices, Greek letters. Live KaTeX preview plus copyable LaTeX source.
Periodic Table
All 118 elements from Hydrogen to Oganesson — Korean and English names, atomic mass, electron configuration, melting/boiling points, and electronegativity. Search by Korean name, English name, symbol, or atomic number.
Time Calc
Add or subtract time from a time of day, or calculate the difference between two times. Supports both 24h and 12h notations. Useful for predicting meeting end times, flight arrivals, work-hour reconciliation, and combining cooking timers.
Hourly ↔ Monthly Wage
Convert between hourly, daily, weekly, monthly, and annual wages based on Korea's 40-hour workweek (209 hours/month including weekly holiday allowance). Shows comparison to the Korean minimum wage. Useful for part-time/contract pay, freelance rate setting, and comparing job posting salaries.
Due Date
Estimate due date, current pregnancy week, and trimester from last menstrual period (LMP) or conception date — based on Naegele's rule. Useful for a rough first estimate before your first OB visit, tracking weekly changes, and planning for delivery.
Scientific Calc
Supports trig, logs, powers, square roots, and other engineering/science calculations. Expression-based input handles long chained calculations. Useful for math/physics/engineering students, engineers, exam prep, and quick statistics.
Percent Calc
All percentage calculations in one screen: N% of X, what percent X is of Y, percent change from X to Y, and X increased or decreased by N%. Useful for revenue change rates, test scores, weight changes, stock returns, and everyday percent math.
Discount Calc
Calculate discounted price from original and rate, find the rate from two prices, or reverse-calculate the original. Useful for checking sale prices, member discounts, stacking card-instant + coupons, and setting up store price tags.
VAT Calc
Auto-calculate supply price (공급가액), VAT, and total at Korea's standard 10% rate. Also reverse-calculates supply price from a VAT-inclusive total. Useful for invoices, tax receipts, audit reviews, VAT filing, and unit-price setting.
BMI Calc
Calculate BMI from height and weight, classified by WHO Asia-Pacific standards: underweight, normal, overweight, and obese. Useful for pre-diet self-checks, interpreting health screening results, insurance prep, and setting target weights.
Compound Interest
Enter principal, rate, and term to compute maturity with compounding. Supports lump-sum deposit and monthly contribution modes. Useful for retirement modeling, education savings plans, long-term return estimates, and simple-vs-compound comparisons.
World Time
See current time in Seoul, Tokyo, New York, London, Paris, Sydney, and more major cities at once. Add/remove cities with real-time updates. Useful for travel and overseas business trips, scheduling video meetings, calling friends/family abroad, and global collaboration.
Random Name Picker
Randomly pick N items from a list. Great for choosing dinner spots, selecting presenters, draw winners, forming class/club teams, and ordering game turns. Powered by Web Crypto for genuinely random, fair results.
Caffeine Tracker
Add up today's caffeine from coffee, tea, and energy drinks, and compare against the 400mg adult daily limit. Useful for cutting back on coffee, gauging dependence, monitoring safe pregnancy intake, and analyzing sleep impact.
Zodiac Sign
Enter your birthday to find your Western 12-sign zodiac, its period, and personality traits. Useful for friend/partner gift inspiration, fun personality readings, and SNS profile zodiac labels.
Chinese Zodiac
Show the Chinese zodiac animal (rat, ox, tiger, rabbit...) and heavenly stem from birth year. Useful for new-year greetings, holiday cards, saju/compatibility inputs, and checking a child's birth-year sign.
Alcohol Converter
Convert alcohol amounts across drink types — soju, beer, wine, whiskey, and more — for equivalent comparison. Useful for gauging your limit at hweshik, calculating sober-up time, and comparing drinks.
BMR Calc
Calculate BMR and activity-adjusted TDEE from gender, age, height, and weight — your baseline calories for cutting or bulking. Useful for meal planning, exercise dosing, and diagnosing weight plateaus.
Running Pace
Enter any two of distance, time, or pace to get the third. Includes finish time predictions for 5K, 10K, half, and full marathon.
Tip Calc
Enter bill total, tip rate, and party size to get per-person share. For US/EU restaurants.
Unit Price Compare
Compare prices of two products of different sizes per unit (100ml, 100g, etc.) to see which is cheaper.
Dice / Coin
Roll various dice (D4, D6, D8, D10, D12, D20, D100) and flip coins. For board games, TRPGs, and decisions.
Rock Paper Scissors
Play rock paper scissors against the computer. Win rate stats included.
Public Holidays
See US federal holidays for this and next year at a glance. Includes floating holidays like Thanksgiving and Memorial Day, computed automatically.
Lunch Picker
Use the roulette when you can't decide. Preloaded Korean/Chinese/Japanese/Western categories, or add your own menus.
Baseball ERA/AVG
Calculate pitcher ERA, hitter batting average, OBP, SLG, and OPS instantly. For amateur baseball and watching games.
Book Reading Time
Estimate how long it'll take to finish a book based on total pages and your reading speed. Uses average Korean reading speed.
Exchange Rate
Enter the rate manually and convert KRW to various currencies or vice versa. Useful for travel budgeting, overseas shopping conversions, and foreign remittance amounts.
Statistics
Enter a list of numbers to get mean, median, mode, standard deviation, variance, quartiles (Q1, Q3), range, and sum in one go. Useful for homework and papers, test score analysis, survey results, and experiment data.
Car Fuel Cost
Calculate driving cost from fuel efficiency (km/L) and gas price. Useful for monthly commute fuel cost, trip fuel estimates, car model comparisons (savings from better mileage), and carpool cost splitting.
Korean Lease Convert
Convert jeonse deposits to monthly rent and back using the conversion rate. Useful for comparing upfront deposit costs when moving, evaluating jeonse vs monthly rent options, and partial deposit + monthly hybrid plans.
Sleep Time
Find optimal wake or bed times based on 90-minute sleep cycles. Useful for deciding nap length after a late shift, optimal bedtime before a morning exam or interview, and jet lag planning.
Blood Donation
Calculate the next eligible donation date based on Korean Red Cross standards using your last donation date and type. Useful for regular donor scheduling, blood donation certificate collection plans, group donation events, and multi-type donation intervals.
Installment Calc
Calculate monthly payment and total fees from principal, rate, and term. Useful for checking affordability before big purchases (appliances, furniture, travel), comparing interest-free installments vs lump sum, and comparing fees across cards.
US Phone Formatter
Normalize phone numbers of any format to a clean US standard like (XXX) XXX-XXXX. Useful for cleaning up Excel/CRM/contact data, handling area codes, and converting to international +1 format.
Korean Biz Number
Validate the checksum of Korea's 10-digit business registration number. Useful for verifying counterparty info, checking before issuing tax invoices, B2B system data integrity, and first-pass risk checks.
Korean RRN
Validate the checksum of a 13-digit Korean Resident Registration Number and extract birth date, gender, and foreigner status. All processing stays in-browser for safety. Useful for form validation, auto-fill UI prototyping, and quickly checking your own RRN digits.
Family Kinship
Enter paternal/maternal relations to see the exact degree of kinship and Korean honorifics (gomo, imo, dangsuk, etc.). Useful for sorting out tricky honorifics at holidays, preparing wedding/funeral greetings, and family tree writing.
Number Format
Convert large numbers to formats like commas (1,000,000), Korean units (100만/1 million), underscores (1_000_000), or scientific (1.0e6). Useful for reports, data tables, readability, receipts, and invoices.
Star Rating
Convert scores to star (★) emoji and copy as text. Half-stars supported. Useful for blog reviews, SNS rating posts, email signatures, and presentation slides.
Golf Handicap
Estimate USGA-style handicap from recent round scores. Useful for self-assessing skill, matching handicaps with partners, setting friendly round betting bases, and tracking seasonal skill changes.
Text (36 tools)
Speech to Text (STT)
Convert speech to text via your microphone. Korean / English / Japanese / Chinese supported. Great for meetings, interviews, lecture notes, and pronunciation practice.
Hanja Dictionary
Look up ~170 common hanja with Korean reading, meaning, stroke count, and Korean Hanja Proficiency Test grade.
Markdown TOC
Automatically analyze H1–H6 headings in your markdown to build a Table of Contents. Indentation and anchor links handled automatically. Great for GitHub READMEs, tech blog posts, Notion pages, study notes, and meeting minutes.
Markdown Table
Set row/column counts, fill in cells, and the markdown table syntax is generated automatically. Add/remove cells, choose alignment, live preview. Great for GitHub README comparison tables, tech blog spec tables, Notion and Obsidian notes, and meeting decisions.
Hangul → Roman
Convert Korean Hangul to romanization using the National Institute of Korean Language's Revised Romanization standard. Useful for English business cards, passport name spellings, overseas hotel reservations, and SNS English nicknames.
Morse Code
Convert text to Morse code and back. Supports English, numbers, and Korean jamo, with audio playback. Useful for Morse learning, amateur radio (ham) exam prep, military comms study, coding study aids, and fun message encoding.
Text-to-Speech (TTS)
Read text aloud with computer voice. Uses OS-installed voices in Korean, English, Japanese, Chinese, and more. Adjustable speed and pitch. Useful for pronunciation practice, accessibility, proofreading by ear, language learning, and recording short announcements.
Word Frequency
Count word and character occurrences in text. Stopword removal and case-insensitive options. Useful for extracting paper keywords, blog SEO keyword analysis, checking overused vocabulary in your writing, and log pattern analysis.
LaTeX Math Editor
Enter LaTeX math and KaTeX renders it live. Supports integrals, sigma, matrices, fractions, Greek letters, and more. Save as PNG/SVG or copy the code. Useful for writing papers, math/physics class materials, embedding formulas in blogs, and building presentation slides.
Number → Korean
Convert 12,345 won to '일만 이천삼백사십오 원' for contracts, receipts, and tax invoices. Auto-adds 일금/원정 formatting. Useful for Korean real estate contracts, lease agreements, IOUs, receipts, tax invoices, and preventing amount forgery.
Hangul ↔ English Keyboard
Convert 'dkssudgktpdy' (English typed on a Hangul keyboard) to '안녕하세요' instantly. Works both ways. Useful for recovering accidentally typed text, fixing messages sent in the wrong layout to KakaoTalk or forums, and debugging password Korean/English confusion.
Character Counter
Count characters, words, and lines in real time. Use for Naver blog, cover letters, papers, college essays, contest entries, newspaper columns, and Twitter/SNS character limits.
Text Case
Convert text to UPPER, lower, Title, camelCase, snake_case, kebab-case, or CONSTANT_CASE instantly. Useful for renaming code variables, keeping filenames consistent, building URL slugs, CSS class names, and DB column names.
Line Sort
Sort multi-line text alphabetically, reversed, by length, or randomly. Case-insensitive and dedupe options. Useful for organizing lists, building word dictionaries, data cleansing, alphabetical indexing, and reference list sorting.
Lorem Ipsum
Generate dummy text for design mockups. Both Latin Lorem Ipsum and Korean filler sentences, by word/sentence/paragraph count. Useful for website mockups, magazine and book layout drafts, mobile app wireframes, and print designs.
Markdown Preview
Type markdown and see live HTML preview. Supports GitHub Flavored Markdown (GFM) and HTML source copy. Useful for previewing READMEs, checking blog posts before publishing, and previewing Notion or Discord message formatting.
Korean Spell Check
Check 100+ commonly misspelled Korean expressions instantly. Processed in your browser without external servers — text is never sent away. Good for quick first-pass checks on KakaoTalk messages, emails, blogs, and SNS posts. This is a beginner/intermediate guide and won't catch context-dependent errors.
Markdown + Math
Render markdown with LaTeX math like $x^2 + y^2 = 1$ in real time. KaTeX-based, exports to PDF — perfect for paper drafts, lecture materials, math/physics/engineering/economics papers, lecture notes, statistics reports, and student assignments.
Text Diff
Compare two texts side by side to see additions, deletions, and changes. Useful for code review, document change tracking, contract revision review, translation comparison, suspected plagiarism check, and resume version control.
Remove Duplicate Lines
Remove duplicate lines from multi-line text. Case-insensitive, whitespace-ignore, and empty-line options. Useful for deduping email lists, data cleansing, word dictionary cleanup, log analysis, and removing duplicate URLs.
Text Reverse
Reverse text by character, word, or line. Useful for KakaoTalk/SNS jokes, flipping sorted data, study material, and mirror-effect designs.
Line Numbers
Automatically number lines in multi-line text, with adjustable start number, separator, and digit padding. Useful for code quotes, meeting note items, name lists, lecture notes, and printable handouts.
Reading Time
Estimate presentation time (WPM) and silent reading time from character count, with adjustable Korean and English speeds. Useful for fitting talks to time slots, prepping speeches, blog 'X-min read' labels, and audiobook length prediction.
Hanja → Hangul
Convert 600 commonly used Hanja characters to their Hangul readings. Useful for reading Hanja in newspapers and magazines, looking up names, decoding old documents and contracts, and Hanja exam prep.
ASCII Box
Wrap text in clean ASCII or Unicode boxes. Useful for code comment headers, README highlights, Discord/Slack messages, decorated terminal output, and stylized menu text.
Encoding Convert
Restore broken Korean (��) when EUC-KR/CP949 files are misread as UTF-8. Useful for opening old text files, broken Notepad CSVs/emails, legacy Hancom Office and Korean government files, and Korean filenames that don't display on GitHub.
Lines → Single Line
Join multi-line text into a single line, or connect with commas, semicolons, or any other separator. Useful for turning a spreadsheet column into a SQL IN clause ('A','B','C'), CSV cleanup, flattening name lists, and building OR keyword queries.
HTML → Text
Strip all tags from HTML and extract body text only. Useful for cleaning up email HTML bodies, copying website text, tidying RSS feeds, pasting cleanly into ChatGPT, and search-friendly text extraction.
HTML → Markdown
Convert HTML to markdown. Useful for blog migrations (WordPress, Tistory, Naver Blog → GitHub, Notion), wiki conversions, moving notes to Obsidian, and cleaning email bodies.
Markdown → Text
Strip markdown syntax (**bold**, [link], # heading, etc.) and leave only the text. Useful for accurate character counts in cover letters or blog posts, sending markdown notes via plain email/KakaoTalk, and clean ChatGPT input.
Text Compress
Compress long text (JSON, code) with LZ-string into short strings. Useful for passing data via URL parameters, creating short shareable links, saving localStorage space, and sharing long code in chats.
Blockquote Maker
Prepend > to text in markdown blockquote or email quote format. Useful for inserting quotes in markdown blog posts, quoting originals in email replies, making Slack/Discord blocks, and writing debate or rebuttal posts.
Word Cloud
Visualize frequently used words by size to make a word cloud. Useful for keyword visualization in presentations, summarizing survey responses, theme analysis of papers and blog posts, and mind map/infographic design.
Emoji Search
Search emojis by Korean or English keyword and copy with one click. Useful for KakaoTalk/Instagram/Twitter posts, decorating Notion page headers, email signatures, GitHub README, and presentation highlights.
Number → English
Convert numbers to English words. Useful for English check writing, international contracts, English invoices, writing/composition, and English exam answers.
Text Stats
Analyze characters, words, sentences, paragraphs, average sentence length, and readability scores in one go. Useful for checking readability of cover letters, blog posts, and papers; evaluating English learning material difficulty; and self-diagnosing your writing.
Developer (65 tools)
Mermaid Diagram
Draw flowcharts, sequence diagrams, Gantt charts, class diagrams, and pie charts from text code. Embed-ready for GitHub README, Notion, Obsidian. Download SVG/PNG.
Age Calculator (Western/Korean)
Enter your birth date and see Western (international) age, Korean counting age, and yeonnai (year age) at once. Reflects Korea's June 2023 standardization to international age. Useful for paperwork, medical prescriptions, insurance, job applications, and confirming legal age for alcohol or tobacco.
Lunar ↔ Solar
Convert Korean lunar and solar dates in both directions. Range 1391–2050, leap month support, and ganji display. Useful for converting your parents' or grandparents' lunar birthdays to solar, ancestral rites date conversion, checking Lunar New Year and Chuseok dates, and entering data for fortune telling.
Caesar Cipher / ROT
Encrypt and decrypt text with Caesar cipher. ROT13/ROT47 presets and custom 1–25 rotation. Useful for CTF challenges, hiding spoilers on forums, introductory cryptography study, and fun message encoding.
HTTP Status Codes
Search the meaning of HTTP response codes 100–599. RFC standard codes plus common non-standard ones (418, 429, etc.). Useful for API debugging, error screen analysis, backend response design, interview prep, and web dev study.
CSS Gradient
Build linear/radial gradients visually by adding and adjusting color stops, then copy the CSS code. Live preview. Useful for website backgrounds, button designs, card UI headers, mobile app gradients, and marketing page backgrounds.
Base Converter
Convert between decimal, binary, octal, and hex instantly. Negatives and decimals supported, with auto-digit grouping. Useful for coding/CS study, color code (#RRGGBB) analysis, IP address conversion, bitwise op debugging, and assembly learning.
HTML Entity
Convert special characters like &, <, >, ", ' to HTML entities (&, <, >) and back. Numeric entities for Korean and emoji are also supported. Useful for safely displaying code samples on blogs, XSS prevention, writing HTML emails, and validating sitemaps and RSS feeds.
Password Strength
Score password strength by length, character types, and predictability. Detects common passwords, repeated patterns, and keyboard sequences. Useful for checking new account passwords, confirming corporate security policy compliance, and security awareness training.
Color Contrast (WCAG)
Calculate contrast ratio between text and background and check WCAG AA/AAA compliance. Useful for design accessibility audits, government and public sector sites (accessibility required), accommodating visually impaired users, and mobile readability checks.
Lotto Number Picker
Generate Korean Lotto 6/45 numbers using Web Crypto's secure RNG. Multiple games at once, with exclude option. Useful for weekly lotto picks, company year-end party games, and school or club random draws.
JSON Formatter
Pretty-print or minify JSON. Reports syntax errors and supports key sorting. Useful for API response debugging, config file review, log/monitoring data analysis, and external data source cleanup.
URL Encoder
Percent-encode Korean and special characters for URLs, or decode them. Supports encodeURIComponent and encodeURI modes. Useful for building API querystrings, analyzing search URLs, recovering broken Korean URLs, and web debugging.
Hash Generator
Calculate SHA-256, SHA-512, SHA-1, and MD5 hashes of text or files instantly. Use for integrity verification and checksums. Useful for verifying downloaded files, checking backup integrity, comparing API signatures, and security study.
UUID Generator
Generate multiple cryptographically secure UUID v4s at once. Supports hyphen and uppercase options. Useful for database primary keys, API identifiers, temporary tokens, tracking IDs, and avoiding filename collisions.
Unix Timestamp
Convert Unix timestamps (seconds or milliseconds) to human-readable dates and back. Supports ISO 8601, local, and UTC display. Useful for database log analysis, API debugging, checking cookie/JWT expiry, and timezone conversion work.
Image ↔ Base64
Encode an image as a Base64 data URL, or decode a data URL back to an image. Useful for inline-embedding images in CSS or email, inline SVG icons, including images in React components, and avoiding caching for tiny icons.
CSV ↔ JSON
Convert CSV data to JSON array and back. First row recognized as header; quoted and comma-containing values are properly handled. Useful for sending Excel data to APIs, processing report data, DB backup cleanup, and data migration.
YAML ↔ JSON
Freely convert between YAML and JSON. Useful for Kubernetes, GitHub Actions, OpenAPI, Docker Compose, and Ansible config files, and quick conversions between the two formats.
SQL Formatter
Pretty-print complex SQL queries. Supports 14 dialects including MySQL, Postgres, SQLite, MSSQL, BigQuery, and Snowflake. Useful for cleaning up code before review, analyzing ORM-generated queries, and recovering one-line queries from logs.
Cron Parser
Enter a cron expression to get a human-readable description and the next N execution times. Supports 5-field and 6-field (with seconds). Useful for writing Linux cron jobs, validating GitHub Actions schedules, AWS EventBridge, and Vercel Cron settings.
IPv4 / CIDR Calc
From CIDR notation (e.g., 192.168.0.0/24), calculate the network address, broadcast, subnet mask, and usable hosts. Useful for designing internal networks, splitting AWS VPC subnets, writing firewall rules, and networking exam prep.
JWT Decoder
Decode JWT header and payload. See expiry and issuer at a glance. No signature verification — use for debugging only. Useful for API auth debugging, expired token diagnosis, OAuth flow analysis, and SSO token inspection.
CSS Shadow
Build box-shadow visually with sliders and copy the code. Supports multiple shadow layers with live preview. Useful for card UIs, button emphasis, modal lift effects, and Material Design elevation.
JSON ↔ XML
Freely convert between JSON and XML. Attribute handling and indent options. Useful for legacy SOAP API debugging, RSS feed processing, analyzing Korean government public API responses, and Korean finance/insurance/telecom data work.
D-Day Calc
Calculate days between two dates, D-day until a specific date, or the date N days from today. Useful for counting down to exams, weddings, military discharge, anniversaries, project deadlines, dating days, birthdays. Korean lunar calendar not supported.
Unit Converter
Convert length (m, km, inch, ft), weight (g, kg, lb, oz), temperature (°C, °F, K), area (m², pyeong, acre), and volume (L, mL, gallon). Useful for converting US-unit movies and cooking recipes, comparing overseas online shopping sizes, air cargo weight, and listing height/weight while traveling.
Regex Tester
Enter a regex pattern and flags (gimsuy) to see live matches. Supports capture groups and replacement preview. Useful for data extraction, writing input validation rules, log analysis, previewing VS Code or IDE search patterns, and learning regex.
Color Converter
Convert between HEX, RGB, and HSL color codes. A free tool for designers and developers. Useful for organizing design system colors, writing CSS, transferring colors from Photoshop/Illustrator, and standardizing brand colors.
Base64 Convert
Convert between text and Base64. URL-safe option supported, with automatic Korean handling. Useful for analyzing API auth tokens, JWT payload decoding, email attachment debugging, and safe data transmission encoding.
Password Generator
Generate cryptographically secure random passwords. Choose length, uppercase, numbers, and special characters. Useful for signing up for new accounts, rotating corporate passwords, setting Wi-Fi router passwords, and generating temporary tokens.
URL Slug
Convert Korean, spaces, and special characters into SEO-friendly URL slugs. Includes optional Korean romanization. Useful for blog post URLs, WordPress/Tistory/Notion page addresses, static site paths, and product URL cleanup.
HTML Minifier
Remove whitespace, comments, and line breaks from HTML to reduce file size. Commonly used for faster production loading, Core Web Vitals improvements, and saving mobile data.
CSS Minifier
Strip whitespace, comments, and unnecessary semicolons from CSS to save bytes. Useful for production optimization, page speed, and reducing CDN costs.
JavaScript Minifier
Minify and mangle JavaScript with Terser, including identifier shortening and dead-code elimination. Useful for library publishing, npm packages, and static site optimization.
JSON Diff
Compare two JSONs object-by-object to show added, removed, and changed keys. Useful for tracking API changes, diffing config files, comparing GraphQL responses, and verifying schema migrations.
Text ↔ Binary
Convert text to bit-level binary and back. Supports both ASCII and UTF-8. Useful for CS study, debugging, cryptography practice, and CTF challenges.
Text ↔ Hex
Convert text to hexadecimal and back. Useful for debugging, encoding checks, network packet analysis, embedded firmware work, and hex dump inspection.
ANSI → HTML
Convert ANSI terminal escape sequences to HTML so you can display terminal colors on web pages, blogs, and docs. Useful for sharing CI/CD logs, replacing screenshots, and showing colored command output in tech posts.
Keycode Viewer
Press any key to see its event properties in real time: key, code, keyCode, and which. Useful for shortcut development, game controls, form key handling, and IME input debugging.
File → Base64
Encode any file (images, PDFs, videos) as Base64 data URLs, and decode data URLs back to files. Useful for inline attachments, embedding small files in code, and turning files into text for debugging.
Unicode Lookup
Look up the Unicode codepoint (U+XXXX) and name of a character, or build a character from a codepoint. Useful for emoji analysis, font compatibility debugging, Hanja code lookup, and special character input.
SVG Minifier
Strip comments, extra whitespace, and editor metadata (Inkscape, Illustrator) from SVG files to shrink size. Useful for web icon optimization, React icon components, and load speed.
Data Size Convert
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Both SI (1000) and IEC (1024) supported. Useful for disk capacity comparisons, bandwidth calculations, file size estimates, and cloud cost projections.
MIME Types
Search by file extension or MIME type, both directions. Useful for HTTP response header configuration, file upload validation, security policy writing, email attachment handling, and web server config.
CSS Colors
All 148 CSS named colors with their HEX codes, searchable. Useful for color inspiration while writing CSS, rapid prototyping, and writing design guides.
HTTP Methods
Summary of HTTP method meanings, usage, and idempotency. Useful for RESTful API design, backend learning, interview prep, and API documentation.
.env Parser
Convert environment variable files to JSON objects, or convert JSON back to .env format. Useful for debugging environment settings, migrating variables across systems, and validating CI/CD environment variables.
Hangul Jamo Decompose
Decompose Hangul syllables into initial/medial/final jamo, or compose them back. Useful for Korean search and autocomplete, IME conversion, phonological analysis, and learning to code Korean text.
Seconds → Duration
Convert numeric seconds (7200) to readable formats (2:00:00 or 2 hours) and back. Useful for video/music durations, log analysis, API response handling, and workout records.
bcrypt Hash
Generate and verify bcrypt hashes with adjustable cost factor. Useful for auth system development, test dummy data, and database checks.
ROT 1-25
Display results for ROT1–25 all at once. Useful for Caesar cipher brute-force decoding in CTFs, quickly finding the right shift when unknown, and cipher learning.
Sensitive Data Mask
Auto-detect and asterisk-mask card numbers, Korean Resident Registration Numbers, phone numbers, and emails. Useful for pre-share log checks, screenshot prep, hiding personal info in blog posts and presentations, and pre-analysis anonymization.
Text Similarity
Calculate Levenshtein edit distance and percentage similarity between two strings. Useful for typo detection, similar-word lookup, search autocomplete, and data deduplication.
Font Preview
Live preview how text looks in any font. Useful for CSS font decisions, website design mockups, Korean font comparisons, and choosing fonts for business cards or posters.
Random String
Generate strings with cryptographically secure Web Crypto random. Useful for API keys, session tokens, temporary IDs and passwords, invitation codes, and UUID alternatives.
User-Agent Parser
Extract browser, OS, device, and version from User-Agent strings. Useful for web log analysis, compatibility debugging, analytics segmentation, and bot/crawler identification.
Password Compare
Evaluate two passwords side by side to see which is stronger. Useful for before/after comparison when changing passwords, showing family or colleagues why weak passwords are risky, and security education materials.
JS Beautify
Re-indent minified or compressed JavaScript for readability. Useful for analyzing external libraries, reading others' code, debugging, and educational code unpacking.
Code to Image
Paste source code, choose a language, and get a beautiful syntax-highlighted screenshot (Carbon-style) as PNG. For blog/SNS sharing, showing off code on Twitter, embedding in Notion or slides, and code review captures. 16+ languages.
HTML to Image
Enter HTML and CSS, then download the rendered result as a PNG. Useful for demo/portfolio previews, design mockups, email template checks, and widget design output. Powered by html2canvas.
SVG Blob
Generate random organic, curved SVG blobs. Use as website background decoration, hero-section accents, logo supplements, or illustration backgrounds. Control complexity, randomness, and color. Copy SVG code or download PNG.
Data URI Generator
Convert images, SVG, or text into Base64-encoded Data URIs. Inline in CSS background-image, embed images in HTML emails, build single-file demos with no external requests, or embed small favicons. Auto-detects MIME type.
File Hash Verify
Upload a file and paste the expected hash to auto-verify integrity. Useful for verifying downloaded files, checking OS ISO/executable tampering, and Git commit matching. Supports MD5, SHA-1, SHA-256, SHA-512. Browser-only processing.
File Split/Join
Split large files into smaller chunks (e.g. 10MB) or rejoin pieces. For email attachment limits, KakaoTalk transfer limits, cloud upload chunking. Splits auto-name `.part1`, `.part2`. Browser-only processing.
PDF (19 tools)
PDF Unlock
Unlock password-protected PDFs (PDFs you own or have rights to). Removes edit/print/copy restrictions; supplying the correct password unlocks open-restricted files.
PDF Merge
Combine multiple PDFs into one. Drag to reorder, and files are processed in your browser and never uploaded.
PDF Split
Split a PDF by page or extract specific page ranges. Receive everything as a single ZIP.
PDF Rotate
Straighten sideways or upside-down PDF pages. Rotate all pages or specific pages by 90/180/270 degrees.
PDF Delete Pages
Remove blank or unnecessary pages from a PDF. Just select page numbers and hit delete.
Images → PDF
Combine photos and scans into a single PDF. Supports JPG/PNG/WebP, choose page size, free reordering.
PDF Reorder Pages
Drag PDF page thumbnails to reorder freely. Rotate and delete pages too. All processing in your browser.
PDF Extract Pages
Pick page numbers or ranges from a PDF and save them as a new PDF. Useful for sharing only certain pages.
PDF Watermark
Add a text watermark (e.g., 'CONFIDENTIAL', company name) to every page of a PDF. Adjustable color, opacity, rotation, and size.
PDF Page Numbers
Automatically add page numbers to each page. Choose position (header/footer, left/center/right), format (1, 1/N, p1), and start number.
PDF Text Extract
Extract body text from a PDF as .txt. Useful for searching or translating. Scanned PDFs (images) may not yield text.
PDF → Images
Save each PDF page as PNG or JPG. Adjustable resolution, batch download as ZIP.
PDF Add Blank Page
Insert blank pages at any position in a PDF. Useful for aligning chapter starts to the right side in duplex printing, matching booklet page counts, adding note space, or inserting break pages between sections.
PDF Metadata
View and edit a PDF's title, author, subject, keywords, and creator info. Useful for stripping internal author info before external sharing, setting standard metadata for archives, and adding SEO keywords.
PDF Crop
Crop top/bottom/left/right margins from every page of a PDF in millimeters. Useful for removing dark scan edges, splitting two-page-spread scans into single pages, or trimming margins to improve tablet reading.
PDF Images Extract
Render each PDF page as a high-resolution PNG and save as a ZIP bundle. Useful for using PDF in slide decks, capturing lecture materials, sharing PDF content on blogs/SNS, and making card news.
PDF N-up
Combine multiple pages into one page in 2x2 or 2x1 layouts for printable booklets and summaries. Saves paper, prints 4-page-per-sheet lecture notes, and makes presentation handouts.
PDF Page Size
Change all pages to A4, Letter, Legal, B5, or other sizes. Useful for converting US Letter PDFs to Korean A4, switching to B5 for booklets. Aspect-preserving mode avoids content clipping.
PDF e-Sign
Draw or upload a signature image directly onto a PDF. For contract signing, consent forms, or quote confirmations. Browser-only processing — no upload. Powered by pdf-lib.
Citation · Essay (8 tools)
Citation Formatter
Enter author, year, title, and journal to generate all five major citation formats at once: APA 7, MLA 9, Chicago, Harvard, and IEEE. Supports journals, books, and websites. Useful for paper writing, thesis references, and conference-format conversions.
DOI · ISBN Lookup
Paste a DOI or ISBN, and CrossRef / Open Library APIs fetch metadata to generate APA, MLA, and Chicago citations. Great for accurate one-click references during paper writing — no more citation typos.
BibTeX Converter
Convert LaTeX BibTeX entries into plain-text APA, MLA, or Chicago references. Helpful when moving a paper into Word or Hancom Office, cleaning up exports from Zotero/Mendeley, or meeting different conference style requirements.
Bibliography Sorter
Sort a reference list alphabetically or by Korean Gananada order, remove duplicates, and preview hanging-indent formatting. Useful for last-minute paper polish, merging references from multiple authors, and citation cleanup.
Title Case Converter
Auto-capitalize English paper or essay titles per APA, Chicago, and MLA rules. Short prepositions and conjunctions stay lowercase. Useful for paper titles, English presentation decks, book covers, and English resumes.
Academic Citation
Auto-generate academic citation entries in APA 7th, MLA 9th, Chicago Author-Date, and Harvard styles — both the reference list entry and the in-text citation. Useful for theses, journal submissions, and student papers.
Text Normalizer (Plagiarism)
Unify quotes, whitespace, line breaks, and Unicode before running Copykiller / Turnitin. Cuts false positives caused by character variants. Useful for thesis self-checks, assignment prep, and final-pass citation accuracy.
Footnote Formatter
Auto-generate footnotes in Chicago Full Note, Chicago Short Note, and Korean humanities styles, including ibid. for repeated citations. Useful for humanities, history, and religion papers, thesis footnotes, and academic publishing prep.