Without a key

These endpoints describe the platform: which venues and instruments are collected, what a query may ask for and within which limits, and whether a query you have written is valid. None of them returns a venue’s figure, so none of them needs a key — you can see what exists, and check your query against the real grammar, before deciding to buy an answer.

The same coverage is published as a page on debyko.com; this is the machine-readable form of it, and it is generated from the same registry the collectors work from, so the two cannot drift apart.