So why this one? Firstly, because it's not jam-packed with ads, and also because - apart from videos - conversions are made browser-side and not server-side.

(via https://sebsauvage.net/links/?es8DAg)

Convert audio to text. The project is an UI for the Whisper tool.

Convert to AVIF

This app doesn’t seem to have any limitations on the number of files or file sizes, but note that the AVIF format is not yet supported in all modern browsers.