TL;DR: I built DevToolkit — a collection of 22 free browser-based tools for developers. No signup, no ads, no tracking. Everything runs locally in your browser.
→ lucasmdevdev.github.io/devtoolkit
Why I built this
I was tired of:
- Tools that require signup to use a JSON formatter
- Sites with 5 cookie banners before you can use a regex tester
- Tools that send your data to a server (your JWT shouldn't leave your browser)
- Slow, heavy tools when you just need to encode some Base64
So I built everything I needed in one place.
What's in it
Formatters
- JSON Formatter — format, validate, syntax highlight
- Markdown Preview — live preview with HTML export
- CSS Formatter — beautify or minify your CSS
- SQL Formatter — format SELECT/INSERT/UPDATE with keyword casing options
Encoders / Decoders
- Base64 — encode/decode text and files
- URL Encoder — percent-encode/decode URLs
- JWT Decoder — inspect token header, payload, expiration (100% local)
- HTML Encoder — escape/unescape HTML entities
Converters
- Color Converter — HEX ↔ RGB ↔ HSL ↔ HSB
- Color Picker — with shade generation and WCAG contrast check
- Timestamp Converter — Unix timestamps to human dates
- Number Base Converter — decimal ↔ hex ↔ binary ↔ octal
- CSV ↔ JSON — bidirectional conversion with type detection
Generators
- Password Generator — with entropy display
- UUID / ULID Generator — v4 UUID, ULID, NanoID
- Hash Generator — MD5, SHA-1, SHA-256, SHA-512 (Web Crypto API)
- QR Code Generator — URL, text, WiFi, vCard
- Lorem Ipsum — paragraphs, sentences, or words
- Cron Helper — build and understand cron expressions
Testers / Reference
- Regex Tester — with match highlighting and groups
- Diff Viewer — side-by-side text comparison
- HTTP Status Codes — complete reference with search, 1xx to 5xx
Privacy first
Every single tool runs 100% in your browser:
- JWT tokens never leave your device
- Hashes are computed locally via Web Crypto API
- No analytics, no tracking, no ads
- No server requests (except QR code which uses a CDN library)
What's next
I'm planning to add:
- XML Formatter
- YAML ↔ JSON converter
- API Response Beautifier
- Certificate decoder (PEM/x509)
- ASCII/Unicode converter
Feedback welcome
The whole thing is on GitHub: lucasmdevdev/devtoolkit
What tools are you missing? Drop them in the comments — if enough people ask for the same thing, I'll build it.
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