About NullKit

NullKit is a one-person project dedicated to building useful, free, and privacy-respecting tools that run entirely in your browser.

The Problem

Too many simple tools require you to download an app, create an account, or upload your data to someone's server. Need to test your microphone? Download this 50MB app. Want to check a data file? Upload it to our cloud. Looking for a pitch pipe? Here are 12 ads before you hear a note.

It doesn't have to be this way.

Our Philosophy

• Browser-first — Modern browsers are incredibly powerful. WebAssembly, Web Audio API, WebGL, WebRTC — these technologies let us build desktop-quality tools that run in a tab.
• Privacy by architecture — We don't just promise privacy, we enforce it. When your data never leaves your device, there's nothing to leak, hack, or sell.
• No artificial limits — No "free tier" with upgrade walls. No "sign up to save". Every feature is available to everyone.
• Fast and focused — Each tool does one thing well. No bloat, no feature creep, no 30-second loading screens.

The Tools

NullKit currently offers four main tools:

• Guandan Trainer — Practice app for China's most popular card game, with AI opponents and puzzle training
• ChoirPitch — Pitch pipe for choir directors and singers, with setlist management and custom tuning
• FileScope — Instant data profiling for Parquet and Lance files, powered by DuckDB WASM
• DeviceTest — 12+ hardware tests for microphone, webcam, speakers, keyboard, screen, CPU, and GPU

More tools are always in development. Each one starts with a real problem that existing solutions handle poorly.

Contact

Questions, feedback, or ideas? Reach out via the project repositories or drop a note through any of the tool pages.