20 Free Developer Tools We Built (And Why We Gave Them Away)

This article was originally published on Jo4 Blog . You know those random utility websites you visit once, use for 30 seconds, and never think about again? We built 20 of them. And put them all in one place at jo4.io/u . No signup. No ads. No "subscribe to access." Just tools. Why Build Free Tools on a Paid Product? We're a URL shortener. People pay us for short links, analytics, and QR codes. So why give away free tools? 1. We Needed Them This is the honest answer. While building jo4, we constantly needed: JWT decoder to debug OAuth tokens Base64 encoder/decoder for API payloads JSON formatter to read webhook responses Timestamp converter to debug expiration issues Hash generator for testing HMAC signatures We were opening random websites, getting hit with ads and popups, and thinking "this is stupid." So we built our own. 2. We're Developer-Friendly Our tagline is literally "Built for developers who ship." If we're going to claim that, we need to prove it. Free tools with no signup,