The documentation at https://github.com/wikitree/wikitree-api/blob/main/getPeople.md does not describe the maximum number of profiles you can request in 1 call. Is there a (preferred) maximum?
It describes the maximum number that can be returned in a single call. The "start & limit" section says
The maximum (and default) limit is currently 1000.
After that, if more results exist, you can get another 1000 by using start=1000, and so on. The successive calls should be spread out in time to avoid being rate-limited.
It depends on what you mean? :). If you are referring to the number of ids you can give in the keys field, I seem to recall it is 1000, but I am not 100% sure. If you are referring to how many profiles you can get (when specifying nuclear, ancestors, descendants, etc), you will not get more than about 10000 profiles back.
Edit: corrected 5000 to 10000 as per the discussion in this thread
Yes, that's what I meant by "depends what you mean". The 100 Ian refers to (I think) is the number of IDs you can place in the keys field. The max number of profiles per returned result is 1000 (irrespective of how many IDs you put in the keys field).
And actually, I think Ian is correct, 100 and not 1000 might be the max number of IDs you can put in the field. Should be easy to test.