Every developer has that moment: you need to decode a JWT, format some JSON, or generate a quick hash — and you end up on some ad-infested site that wants your email before showing results.
I got tired of it. So I built 13 free, browser-based developer tools that run entirely in your browser. No sign-ups. No tracking. No server calls. Just open and use.
Here's the full lineup 👇
Why Browser-Based?
Before we dive in, here's why every tool runs 100% client-side:
- 🚀 No installation — Works on any device with a browser
- 🔒 Privacy first — Your data never leaves your machine
- 📡 Works offline — Most tools function without internet after first load
- ⚡ Instant — No API calls, no loading spinners, no rate limits
The 13 Tools
1. 🔧 JSON Formatter & Validator
Paste messy JSON, get it beautifully formatted with syntax highlighting. Pinpoints exact error locations when validation fails.
Use case: Debugging API responses at 2 AM without leaving your browser.
2. 🔍 Regex Tester
Real-time regex testing with match highlighting, capture group extraction, and a built-in cheatsheet.
Use case: Crafting that perfect validation pattern without guessing.
3. 🔐 Base64 Encoder/Decoder
Encode and decode Base64 strings instantly. Handles text, files, and Unicode (yes, emoji too 🎉).
Use case: Decoding that mysterious Base64 blob in your JWT payload.
4. 🔗 URL Encoder/Decoder
Shows both encodeURI and encodeURIComponent results side by side — so you finally learn the difference.
Use case: Fixing broken query parameters in redirect URLs.
5. #️⃣ Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes using the native Web Crypto API. Supports file hashing too.
Use case: Verifying file integrity after downloads.
6. 🎨 Color Picker & Converter
Convert between HEX, RGB, and HSL. Includes a palette generator and WCAG contrast checker.
Use case: Making sure your UI meets accessibility contrast ratios.
7. 📝 Lorem Ipsum Generator
Generate placeholder text by paragraphs, sentences, or words. Outputs plain text or HTML.
Use case: Filling mockups without copy-pasting from sketchy websites.
8. ⏱️ Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates. Supports seconds and milliseconds.
Use case: Decoding that
1708099200in your database logs.
9. 🔑 JWT Decoder
Paste a JWT and instantly see the decoded header, payload, and signature. No libraries needed.
Use case: Debugging auth tokens without installing jwt.io's dependencies.
10. 🎨 CSS Gradient Generator
Create beautiful linear and radial gradients with a visual editor. Copy the CSS with one click.
Use case: Designing that perfect hero section background in seconds.
11. 🔒 Password Generator
Generate cryptographically secure passwords with customizable length, symbols, and character sets.
Use case: Creating strong passwords without trusting a third-party service with your security.
12. 📄 Markdown Preview
Live markdown editor with instant preview. Write on the left, see the rendered output on the right.
Use case: Drafting README files before pushing to GitHub.
13. 🔍 Website Audit Tool
Quick client-side audit of any website — checks meta tags, headers, performance hints, and SEO basics.
Use case: Sanity-checking your site's SEO before launch.
The Stack
All 13 tools share the same philosophy:
- Vanilla HTML/CSS/JS — No frameworks, instant load times
- GitHub Pages — Free hosting with global CDN
- Dark mode first — Because we're developers
- Mobile responsive — Works on your phone too
Total bundle size for all 13 tools? Less than what a single React app's node_modules weighs. 😄
Want the Full Collection?
All tools are open source and free to use. If you find them useful and want to support the project, I've bundled the complete source code with setup guides on Gumroad:
👉 Get the Developer Tools Collection on Gumroad
Pay what you want — including $0. It's my way of giving back to the dev community.
What's Next?
I'm actively building more tools based on what developers actually need. Got a suggestion? Drop it in the comments!
Currently thinking about:
- Cron expression parser
- SVG optimizer
- CSS unit converter
Star the repos on GitHub if you want to follow along. And if you use any of these tools in your workflow, I'd love to hear about it. 🙌
Built with ☕ and AI assistance. All tools are free and open source.
🚀 Want More?
I'm building an AI-powered revenue machine that runs 24/7 — from micro-SaaS tools to games to digital products, all automated with AI agents.
Follow me here on Dev.to to get weekly insights on:
- 🤖 AI automation that actually makes money
- 🎮 Game dev with AI agents (Godot + TDD)
- 🛠️ Building micro-SaaS tools from scratch
- 📈 Indie hacker growth strategies
🤖 More From Me
🛠️ 18+ Free Dev Tools — Browser-based, no install needed.
🎮 27+ Browser Games — Built with AI agents.
📦 AI Agent Prompt Collection — Templates for your own setup.
If this was useful, drop a ❤️ — it helps more devs find it!
Got questions? Drop them in the comments — I read every one.
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