Editor's Picks
QR Code Generator
Paste any URL or text and get a downloadable QR code instantly — adjustable size and error correction, runs locally in your browser.
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 digests for any text, grouped into 4-char chunks for easy comparison. Everything runs in your browser.
Moon Phase
See tonight's moon or any date: an astronomically-correct disc, illumination %, moon age and lunar day-of-month. Drag the lunation arc to sweep the terminator continuously. Includes a birth-moon share card.
Reversi
Play Reversi — the disc-flipping classic — against four AI levels. The beginner is beatable; the master solves the endgame exactly. Legal moves are marked, undo is one tap, and it's one-thumb friendly.
Image Compressor
Compress JPEG, PNG, and WebP images in your browser — 100% local, no upload. Side-by-side before/after preview and a quality slider for live size-vs-quality decisions.
Taiwan ID Validator
Check Taiwan national ID format, checksum, and prefix.
This Week
Bilingual Tone Checker
Paste a message, see how warm, formal, or direct it reads.
JSON Formatter
Pretty-print, minify, or validate JSON with error location hints.
Forgetting Curve Vocab
Learn English vocabulary using Ebbinghaus forgetting curve spaced repetition. 5 minutes a day with pronunciation and example sentences.
Explore by Category
AI
- Bilingual Tone Checker
- Token Visualizer
Quant
- Compound Interest / CAGR Calculator
- DCA Calculator
- Kelly Calculator
Dev
- Base64 Encoder / Decoder
- Binary Bit Visualizer
- CSS Minifier / Beautifier
Games
- Block Stack
- Five-Letter Grid
- Gomoku
Local
- ROC / Gregorian Year Converter
- Taiwan ID Validator
- Uniform Invoice Validator
Design
- Aspect Ratio Calculator
- Color Converter
- Image Compressor
Text
- Character Word Counter
- Diff Checker
- Markdown Cleaner
Time
- Breath Pacer
- Unix Timestamp Batch Converter
Learn
- Bopomofo Practice
- Chengyu Guess
- Chord Finder
Frequently Asked Questions
What is kbwen Lab?
kbwen Lab is a collection of free, lightweight browser tools for quant math, developer tasks, Taiwan-specific formats, and casual games. All tools run entirely in your browser with no sign-up required.
Are all tools free?
Yes. Every tool on kbwen Lab is free to use with no account needed.
Is my data private?
All tools run locally in your browser. Your data never leaves your device unless a tool explicitly states otherwise.
Do I need to create an account?
No. All tools work instantly in your browser — no sign-up, no login, no installation.
What categories of tools are available?
kbwen Lab covers nine categories: AI, quant, dev, games, local, design, text, time, and learning tools.
Can I use these tools on my phone?
Yes. All tools are responsive and work on mobile browsers. No app download is needed.