I Built 10 Free Developer Tools That Run Entirely in Your Browser

As developers, we constantly reach for small utilities — formatting a JSON blob from an API response, decoding a Base64 string, generating UUIDs for a database seed, or testing a regex pattern before committing it. Most online tools work fine, but they come with trade-offs: walls of ads, slow load times, or the uncomfortable reality that you're pasting potentially sensitive data into someone else's server. So I built DevTools Hub — a collection of 10 developer utilities that run entirely in your browser. No backend. No data leaves your machine. No accounts or cookies. The Tools Here's what's included: JSON Formatter & Validator — Beautify, validate, or minify JSON with instant error detection. Base64 Encode/Decode — Convert text to Base64 and back, handling UTF-8 properly. UUID Generator — Generate random v4 UUIDs in bulk (up to 1000 at a time). Hash Generator — SHA-1, SHA-256, and SHA-512 hashes using the Web Crypto API. URL Encode/Decode — Percent-encode special characters or dec