I built 39 free browser-based dev tools — here's every decision I made and why

Mathew Addala — Wed, 27 May 2026 19:40:43 +0000

I got tired of the same thing happening every day.

Google "json formatter online." Land on a site from 2011. Click format. Get an ad popup. Format the JSON. Close the tab. Repeat tomorrow.

So I built BuiltItDev — 39 developer tools that run entirely in your browser. No accounts. No paywalls. No data leaving your machine.

Why client-side only?
You're pasting API keys, JWT tokens, internal JSON — that data shouldn't hit someone's backend.

Everything processes locally. Hash generation uses the Web Crypto API. JWT decoding splits and base64-decodes in the browser. No network calls. Nothing logged.

Stack
Next.js 16 App Router + TypeScript. 49 static routes, fully pre-rendered. Each tool is its own route (/tools/json-formatter, /tools/base64) so every page can rank independently on Google.

Tools so far
Category Examples
Encoding Base64, URL encoder, HTML entity encoder
Formatting JSON formatter, Markdown previewer, XML formatter
Generators UUID, Lorem ipsum, Hash (MD5/SHA family)
Converters Color (HEX/RGB/HSL), Timestamp, Number base
Dev utils Regex tester, JWT decoder, Cron parser, Diff checker
39 total. More shipping based on requests.

What I want from you
What tool do you write as a throwaway script every few months because no clean browser version exists? Drop it in the comments — I'll build it.

→ builtitdev.com

DEV Community: Mathew Addala

I built 39 free browser-based dev tools — here's every decision I made and why