Using the tool
The converter is offered free of charge and without an account. It accepts public YouTube links and returns an MP3 file. It may be changed, rate-limited or withdrawn at any time, and it is not warranted to convert any particular link — the failures page names the cases where it cannot.
Your responsibility
You are responsible for having the right to convert the audio you submit, and for what you do with the result. Converting audio for your own listening is a different act from publishing it; the copyright page sets out where that line falls. You also agree not to use the tool to automate bulk conversion, to attack the service, or to convert material you are not entitled to.
Availability and liability
The service is provided as-is, without warranties of any kind, and conversions may fail when YouTube changes what it serves or when a video is restricted. The site is not liable for files that expire before you download them or for any loss arising from a failed conversion.