This site is free to use and has no accounts. There is nothing to sign up for and we do not charge for anything here. You do not need to ask before using it for personal or commercial work.
Everything runs in your browser. Your images are not uploaded to us, which also means we cannot recover them: if you close the tab before saving, the work is gone. Keep your originals.
The tools come with no warranty. They are written carefully and tested against a real image collection, but image encoders have edge cases and a file that matters to you may behave differently from our samples. Check the output before you delete the original. If a result looks wrong, the address on the about page reaches me, and a concrete example is more useful than a description.
Two specific promises, because they are the ones people rely on: the PNG path does not change pixels, and the JPEG path does not silently downgrade your chroma sampling unless you turn that option off. Both are measured in the articles linked from the guides page, with the raw numbers published.
The measurement data on the datasets page is published under CC BY 4.0, which is a separate and more permissive licence than these terms. Use it for anything as long as you say where it came from.
Nothing here is legal advice, and nothing here claims to be.