Here’s @matt’s recent presentation at QCon which you can watch, with a split screen displaying the slides here.
https://videoh.infoq.com/presentations/17-mar-guildingabankwithgo-2.mp4
This is a great summary of the talk too -
https://www.infoq.com/news/2017/03/monzo-bank-golang
You can view Matt’s slides from the talk, which include lots of diagrams of Monzo’s microservices architecture, here -
https://speakerdeck.com/mattheath/building-a-bank-with-go-qcon-london-march-2017
it also includes this chart showing rapid growth of Monzo’s services
as well as a diagram, showing how much communication there is between Monzo’s backend services (each line is a message), when you make a transaction
And check out Monzo’s open source Typhon framework, “a transport layer for microservice [RPC] communication” here -
https://github.com/monzo/typhon
while Monzo’s Phosphor application is used for distributed tracing -
https://github.com/monzo/phosphor
PS Monzo are currently hiring engineers