The Problem
Every developer has been here: you need to decode a JWT from production, format a JSON response with customer data, or test a regex against real log entries. So you Google "JWT decoder" and land on some random site plastered with ads, cookie banners, and — here's the kicker — your data gets sent to their server.
Most online developer tools phone home. Your production tokens, API responses, and customer data pass through someone else's infrastructure. We've all done it without thinking twice.
I decided to build something better.
DevToolbox
DevToolbox is a suite of developer utilities that runs entirely in your browser. No server calls. No tracking. No ads. Your data never leaves your machine.
Tools available now:
🔧 JSON Formatter — Format, validate, and minify JSON with syntax highlighting and a collapsible tree view. Handles large payloads without breaking a sweat.
🔐 Base64 Encoder/Decoder — Encode and decode text or files. Supports URL-safe Base64. Drag-and-drop file uploads.
🎫 JWT Decoder — Paste a token, see the header, payload, and signature. Color-coded sections, expiry status, and human-readable timestamps.
🔍 Regex Tester — Live pattern matching with group highlighting. Includes a quick-reference cheat sheet and common pattern library.
🔗 URL Encoder/Decoder — Encode and decode URI components. Handles special characters correctly.
️⃣ Hash Generator — Generate SHA-256, SHA-1, MD5, and more from any text input.
🎨 Color Picker & Converter — HEX ↔ RGB ↔ HSL conversion with a visual picker, contrast ratio checker, and shades/tints palette generator.
⏱️ Unix Timestamp Converter — Bidirectional timestamp↔date conversion with a live ticking clock, auto-detection of seconds vs milliseconds, and quick-jump buttons.
Why Client-Side Matters
Here's what happens with most online tools:
You paste a JWT → It goes to their server → They decode it → They send it back
With DevToolbox:
You paste a JWT → JavaScript in your browser decodes it → Done
No network request. Open your browser's DevTools, check the Network tab — you'll see zero requests after the page loads. It even works offline.
The Tech
Deliberately boring:
- Vanilla HTML/CSS/JS — No React, no build step, no node_modules
- GitHub Pages — Free hosting, HTTPS included
- Dark mode by default — Because developers don't want flashbangs at 2am
- Keyboard shortcuts — Ctrl+Enter to process, Ctrl+L to clear
- Mobile-friendly — Responsive design, works on phones and tablets
Each page loads in under 100ms. No framework overhead, no bundle splitting, no hydration delays. Just HTML and JavaScript doing what they were designed to do.
What's Next
I'm actively building more tools based on what developers need most:
- Diff Checker — Side-by-side text comparison
- Markdown Preview — Live rendering with GitHub-flavored markdown
- YAML/TOML Converter — Convert between config formats
- Cron Expression Parser — Human-readable cron schedule descriptions
Try It
👉 dannycranmer.github.io/devtoolbox
It's free, open source, and always will be. No signup, no paywall.
If you find it useful, buy me a coffee ☕
What tools would you want added next? Drop a comment — I'm building based on what developers actually need.
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