Solo dev's lesson from building 91 free browser tools — what should I build next?

Hey PH 👋

Started keyboardtester.click 2 years ago because I bought a used mechanical keyboard online and had no easy way to test if all the keys actually worked.

Built 1 tool for myself, posted it, and people kept asking "can you also test mice / monitors / mics?" — 91 tools later, here we are.

Some I'm proud of:

- Keyboard tester with NKRO + ghosting + cat-progress gamification

- Dead pixel + frame-skipping + monitor sharpness test

- Hearing-age test (8 kHz – 22 kHz, mosquito tone included)

- Online ruler — actual cm/inches, calibrated by overlaying a credit card

Everything browser-based, free, no install, no signup, in 8 languages.

Question for you all: what testing tool do you wish existed but doesn't? What hardware / browser thing would you want to verify in 30 seconds without installing anything?

Honest answers welcome — I'm always looking for the next one to build.

Site: https://keyboardtester.click

Open source: https://github.com/nasirazizawan009/keyboardtester-click