AIFF is Apple's uncompressed audio format - WAV's counterpart from the Mac side of the world, and still what Logic and older Pro Tools sessions use. It stores its sample rate as an 80-bit extended float, a piece of 1980s exotica most converters get wrong.
Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop an AIFF file above and choose afterwards.