I Built 8 Free Browser-Based Developer Tools (No Uploads, No Tracking)

'## What I Built

Eight developer tools that run entirely in your browser — no files uploaded, no server-side processing, no tracking.

Tool	Description
JSON Formatter	Beautify, validate, compress JSON. CSV export
Image → Base64	Drag & drop, instant Data URI generation
SQL Formatter	Pretty-print with keyword highlighting
Markdown → HTML	Real-time GFM preview with code blocks
UUID Generator	Crypto-secure UUID v4 + ULID
Regex Tester	Real-time match highlighting
Timestamp Converter	Unix seconds/ms ↔ date
Diff Checker	Line-by-line comparison

Why

Every other online dev tool uploads your data. These run 100% client-side — nothing leaves your browser.

Tech

Pure HTML/CSS/JS. Zero frameworks. Under 30KB. Loads in 50ms.

Try

👉 https://matengtian.github.io/devtools/

Feedback welcome! What tool should I add next?