Transparency is the thing to watch
JPEG has no alpha channel. A WebP with a transparent background becomes a JPEG with a solid one, and the colour it picks up is whatever the converter decides — usually black, which is rarely what anyone wants. This tool composites onto white before encoding, which is the sane default, but if your image relies on transparency you want PNG instead.
For a photograph with no transparency, JPEG is the right target and will usually land close to the WebP in size at a sensible quality. For a logo or a screenshot with flat colour, both are the wrong answer and PNG will be smaller as well as sharper.
Nothing is uploaded
The conversion runs in this tab. There is no upload step, so no queue, no daily limit and no account — and you can disconnect from the network and it still works. The same engine powers theimage converter, which handles any combination and unlimited batches, and theimage compressor, which makes a file smaller without changing its format. Both sit underConverters.