The link format
A LoopLab loop is a plain URL. There is no API key, no library and nothing to install. If you can build a string, you can make a loop.
The shape of it
v- The YouTube video id. Eleven characters, the part after
watch?v=. a- Where the loop starts, in seconds. Decimals are fine:
37.2. b- Where it ends, in seconds. Must be greater than
a.
Optional
m- A message. The recipient meets it full screen before the loop plays. Up to 180 characters, percent-encoded.
s- Who it is from. Up to 40 characters, percent-encoded. Only shown alongside a message.
r- Playback rate, between
0.25and2. Pitch stays correct.
A loop with a note on it:
If you would rather call something
One endpoint, GET, no key. It builds the same URL described above, so use whichever is less work.
Returns:
{ "ok": true, "url": "…", "videoId": "…", "a": 37.2, "b": 62.8 }
v accepts a bare id or any YouTube URL, so a caller holding a watch link does
not need to know which part of it matters.
For an AI reading this
There is a machine-readable summary at /llms.txt. It
says the same thing in fewer words.
What this will not do
It will not download, extract or store video or audio, and it will not return video metadata in bulk. Playback happens inside YouTube's own embedded player, so ads run and views count. Those are refusals by design rather than gaps, and they are the reason LoopLab can exist at all.