I Built 25 Free Developer Tools That Run Entirely in Your Browser

Kiel Malpass — Tue, 10 Feb 2026 16:53:50 +0000

Last year I caught myself doing something dumb. I was debugging an authentication issue and pasted a production JWT token into the first online decoder Google gave me. The token had user emails, roles, and session data in its claims. I sent all of that to a server I knew nothing about.

That bugged me. So I started building AllDevBox.

The Problem With Online Dev Tools

We all use them. JSON formatters, base64 encoders, regex testers, SQL formatters. They're everywhere, and most of them work fine. But almost all of them send your input to a server.

For a lorem ipsum generator, who cares. But for a JWT decoder? A SQL formatter that sees your schema? A hash generator where you're testing password inputs? That's a different conversation.

I'm not saying these tools are malicious. Most aren't. But the question is simple: if you can get the same result without your data leaving the browser, why wouldn't you?

So I Built 25 Client-Side Tools

AllDevBox is a collection of 25 developer tools that run entirely in your browser. After the initial page load, zero network requests. Your data stays on your machine.

Here's the full list:

Formatters & Converters

JSON Formatter — prettify and validate JSON
SQL Formatter — format SQL queries
CSS Minifier — minify CSS
JSON to CSV — convert JSON arrays to CSV
YAML to JSON — convert between YAML and JSON
Markdown Preview — live markdown rendering
SVG to PNG — convert SVG files to PNG in the browser

Encoding & Hashing

Base64 Encoder/Decoder
URL Encoder/Decoder
HTML Encoder/Decoder
Hash Generator — MD5, SHA-1, SHA-256, SHA-512
JWT Decoder — decode and inspect JWT tokens

Generators

UUID Generator — v4 UUIDs
Password Generator — configurable secure passwords
Lorem Ipsum Generator

Testing & Reference

Regex Tester — test patterns with live matching
Diff Checker — compare text side by side
Cron Parser — human-readable cron explanations
HTTP Status Codes — quick reference

Utilities

Timestamp Converter — Unix ↔ human dates
Color Picker — HEX, RGB, HSL
Chmod Calculator — visual Unix permissions
Git Command Generator
IP Lookup
Text Case Converter — camelCase, snake_case, etc.

Technical Decisions

I made a few deliberate choices that I think are worth talking about.

No Frameworks

Every tool is vanilla JavaScript. No React, no Vue, no Svelte. This wasn't ideological — it was practical. Each tool is a self-contained page with a textarea and some logic. Adding a framework would mean adding a build step, a bundle, and loading time that users would feel.

The result: every tool loads almost instantly. There's no hydration delay, no JavaScript bundle to parse. The page is ready when it renders.

Hugo for Static Generation

I use Hugo for static site generation. With 25 tools that share a common layout, Hugo's templating keeps things DRY. Each tool is a content file with its own JavaScript, and Hugo handles the rest.

Hugo also builds the entire site in under a second, which makes development fast.

No Build Pipeline

There's no webpack, no Vite, no esbuild. The JavaScript files are written as plain ES modules or inline scripts. This keeps the project simple enough that anyone can clone it, edit a tool, and see the result without installing anything.

No Analytics

No Google Analytics, no Plausible, no tracking pixels. I genuinely don't know how many people use the site, and that's fine. The tradeoff of adding tracking to a tool that promises privacy felt wrong.

What I Learned

Vanilla JS is underrated. The web platform has gotten really good. Between the Web Crypto API (for hashing), the Clipboard API, and modern DOM methods, you can build useful tools without importing a single dependency.

Consistency is hard. Building one tool is easy. Making 25 tools feel like they belong together — same interactions, same layout, same error handling — takes real effort.

Scope creep is fun. I started with 5 tools I used daily. Then "just one more" happened 20 times. Each tool is small enough that adding one feels trivial, but the collection keeps growing.

What's Next

I have a list of tools I want to add — a JSON schema validator, a cURL to code converter, a color contrast checker. If you have ideas, I'd genuinely like to hear them.

The site is free and I plan to keep it that way. No accounts, no paywalls, no "premium tier."

Check it out: https://alldevbox.com

DEV Community: Kiel Malpass