Firestore supported characters for custom id's

Question

I would like to create a custom id for my documents in firestore, I know all the base 62 (a-z, A-Z, 0-9) characters are supported for custo

Answer 1

This is a late answer, but as I was just looking for this information myself:

The constraints on the document ids (and collection ids are) are:

• Must be valid UTF-8 characters
• Must be no longer than 1,500 bytes
• Cannot contain a forward slash (/)
• Cannot solely consist of a single period (.) or double periods (..)
• Cannot match the regular expression __.*__

Document Ids may contain space characters.

The naming constraints on document Ids, collection Ids, and field names are fully documented here:

https://firebase.google.com/docs/firestore/quotas#limits

Google firebase group discussion on this:

https://groups.google.com/forum/#!topic/firebase-talk/bUMpQwGe08k