I provided software engineering services to KrakenFlex on a contract basis.
The work was Python with asyncio, on a serverless AWS architecture: Lambda, SAM and CloudFormation, with DynamoDB for storage and SNS and SQS between the services.
Event-driven services talking to each other over SNS and SQS are straightforward to reason about one at a time and much harder to reason about together, which is a large part of why I later built a local AWS simulator for testing this kind of system.