About

What this site is

Koumen Tools is a collection of small utilities for the things people do every day: splitting a bill, converting a file, checking a number, formatting text. No account, no install, no fourteen-step onboarding. Open the page, get the answer, close the tab.

How we build

In the browser first. Wherever it is technically possible, the work happens on your device. Your numbers, text, and images do not need to be uploaded to a server to get a result — which makes the tools faster and private by default.
One job per page. A tool that does six things badly is worse than a tool that does one thing well. Each page answers one question.
No dark patterns. The free version stays usable. If you pay, it is because the paid version saves you time, not because we broke the free one.

Who runs it

Koumen Tools is built and maintained by an independent developer with a background in WordPress and web performance. It is a small operation: one person, a few servers, and a growing list of tools.

How it is funded

Two ways: paid Pro licences for people who want the extra features, and affiliate links on some recommendation pages. When a link earns us a commission, we say so on the page — see the Affiliate Disclosure. There are no ads tracking you around the web.

Get in touch

Bug reports, feature requests, and complaints all go to the same place: support@koumen.net. We read everything, and we usually reply within two business days.

If a tool gives a wrong number, tell us what you entered and what you expected. That is the single most useful email we can receive.

The paperwork

Last updated: 1 November 2026