API Tokens: A Tedious Survey. Thomas Ptacek reviews different approaches to implementing secure API tokens, from simple random strings stored in a database through various categories of signed token to exotic formats like Macaroons and Biscuits, both new to me.
Macaroons carry a signed list of restrictions with them, but combine it with a mechanism where a client can add their own additional restrictions, sign the combination and pass the token on to someone else.
Biscuits are similar, but “embed Datalog programs to evaluate whether a token allows an operation”.