I Built 22 Dev Tools with Zero Backend — Architecture and Lessons

Why Client-Side Only? Every online developer tool I used was either covered in ads, required an account, or sent my data to a server. I wanted something better. So I built 22 tools that run entirely in your browser. No backend. No API calls. No tracking. The Tools JSON Formatter & Validator Base64 Encoder/Decoder Hash Generator (MD5, SHA-1, SHA-256 via Web Crypto API) JWT Decoder Unix Timestamp Converter Regex Tester with live highlighting Color Converter (HEX/RGB/HSL) Markdown Preview URL Encoder/Decoder Lorem Ipsum Generator Text Diff Tool Password Generator with strength meter Cron Expression Parser QR Code Generator (Canvas API, no library) UUID Generator (bulk mode) Unix Permissions Calculator SQL Formatter (custom parser) YAML/JSON Converter Aspect Ratio Calculator 20-22. Solana tools (token lookup, wallet checker, SOL calculator) Architecture Decisions No external dependencies for core logic. The QR code generator uses raw Canvas API. The SQL formatter is a custom tokenizer. The