PyPI index vs simple index

Question

I've seen mention both an index and a simple index in relation to PyPI, an example is here in the devpi documentation. Is there some difference between the two indexes? Are they the same or do they have different access controls or functions for example?

Answer 1

The "simple" index protocol is read-only, intended for automated use, and is defined in PEP 503. Other protocols with more functionality may be defined by particular repository servers, but are probably only usable with that server's own tools.