Speed up your daily dev workflow with 20 free online developer tools at zaerp.com. Every tool is a single self-contained HTML file with zero external dependencies — no JavaScript libraries loaded from CDNs, no server calls, no tracking. All processing happens locally in your browser.
This makes the tools ideal for sensitive data like JWT tokens, password hashes, or proprietary JSON — your input never leaves your device. The tools are also installable as PWA and work offline once loaded.
Categories: JSON tools (formatter, diff, schema, CSV↔JSON), Encoding (Base64, Base64 Image, URL encoder, HTML entities, charset), Regex (tester + visualizer), Crypto (hash generator, JWT decoder), Reference (HTTP status, MIME types, user-agent parser), and more.
Yes. All 20 developer tools are 100% free, no signup, no install, no API limits. Every tool runs entirely in your browser as client-side JavaScript.
No. All processing happens locally in your browser. Your JSON, tokens, URLs and other inputs never leave your device. This is critical for sensitive data like JWT tokens or password hashes.
Once the page is loaded, yes. The tools have zero external dependencies, so they continue to work even if your internet connection drops.
Yes. Every tool is responsive and works on iOS Safari, Android Chrome and any modern mobile browser. Some tools like JSON Formatter are especially useful when debugging on the go.