20 Free Developer Tools That Run Entirely in Your Browser

I've been building browser-based developer tools for the past year or so. What started as a single OG image generator turned into a full collection of 20 free utilities. They all run in your browser, which means your data never hits a server. I want to walk through all of them, grouped by what you'd actually use them for. Why browser-only tools matter Speed is the obvious reason. There's no round trip to a server, no waiting for a response. Paste your text, get your result. But the real reason is privacy. Think about what developers paste into online tools. JWT tokens with user data. API keys in Base64 strings. Config files with database credentials. Password hashes. Every time you use a server-side tool, that data leaves your machine and lands on infrastructure you don't control. These tools use the Web Crypto API, TextEncoder, and native browser APIs to do everything locally. Your input stays in your browser tab and nowhere else. Debugging and data inspection When something breaks, y