About LZ Tool Box

LZ Tool Box is a collection of free online tools that each solve one small problem quickly and without fuss. Test a keyboard, check a microphone, calculate a resistor value or measure your reaction time, all without installing anything or creating an account.

The site is created and run by Pasindu Senavirathna.

How the tools are built

• Accuracy first. Calculators use standard engineering formulas and show them next to the result. Where results depend on assumptions (for example, conductor temperature in a voltage drop calculation), the page says so.
• Privacy by design. The tools run in your browser. Device tests that use your camera or microphone process everything locally. Nothing you enter is sent to our server.
• Fast and simple. Pages are lightweight, work on mobile and support dark mode.

Free, supported by ads

LZ Tool Box is free to use and funded by advertising. Ads help keep every tool free and pay for new ones.

Found a mistake or have an idea?

If a result looks wrong, a tool doesn't work on your device, or you'd like a new tool, please get in touch.