It’s great that a working UK bank has developed an API. I’m starting to develop my idea with it.
The Open Bank Project have been developing an API that will work with any bank, so third party developers don’t have to adapt their applications to work with different banks.
As a developer, it would be great if Monzo and OBP were working together. Is this something Monzo has thought about?
It is only the big dinosaur banks that are working with the Open Bank Project. Newer banks like Monzo, Fidor etc have their own APIs as their systems newer and they plan to use their APIs to enable things for their friends the customers rather than churn out an API just to do enough to stop those pesky customers switching 
The OBP APIs aren’t nice. Personally I strongly prefer Mondo’a API.