UnitConversionBot

UnitConversionBot skips menus entirely. You type a value and a unit pair in plain text — "10 km to miles", "100 ft to m" — and it replies with the converted number. In group chats the same request goes through the /convert command, so it does not clutter the conversation for people who are not using it.

Behind the scenes it covers the practical categories most people actually need: length, area, volume, weight, temperature, energy and speed. The project is open source and hosted on GitHub under its author's "maltsev" account, running on AWS Lambda — you can read the exact conversion logic yourself rather than trusting a black box. As a secondary feature it can also convert currency, though that is not its main job and shouldn't be the reason you install it.

What it does not have is any kind of onboarding flow or inline mode. It is a small, single-purpose tool built by one developer, so treat it as a fast pocket converter rather than a polished product — there is no visible support channel if something stops working, and updates depend entirely on that one maintainer's spare time.