Nowadays, microservices architecture is at the peak of every organization in order to scale system and team hypergrowth. At N26 (Payments Cards Group Specifically) we started this journey of the monolith to microservice around a year back and we are almost to the end of new highly scalable, domain-driven microservices architecture.

We had to move the card lifecycle related functionality from our monolith service to new microservices solely responsible for card management (ordering, block, unblock, settings and limits etc). When we started this project in our team, there were no product (feature) requirements as such. The entire team goal was to move functionality to the new service(CMS - Card Management System). But later we had to support multiple customer-facing features in this journey. We took the approach of making both services running on life with shared functionality instead of building an entirely new system and switching all traffic to there.

This talk is all about the technical blockers that we had. It focuses on how we managed to not have downtime, maintenance mode, better customer experience, system quality using best engineering practices - This talk will include those strategies. It is also true that not everything is possible to do with engineering, sometimes other roles also help us to solve such challenges like PO/QA/Leads, even customers. Hence, the last part in the title - *Where everyone has to pay*. How each and every stakeholder helped the team to move the architecture - will be part of my talk. How we managed to give the best N26 feature to customer – YOU card color - https://n26.com/en-de/you-bank-account-with-travel-insurance, even in the middle of the migration.

Outline/structure of the Session
1. Highlight on why monolith to microservice - 5 min
2. Introduction to N26 journey to microservice with the problem statement - 5 min
3. Engineer practices helped us to services - we call it a - migration framework - 15 min
4. Stakeholders role in solving each problem - a perspective - 15 min
5. Q&A - 5 min

Learning Outcomes

1. Why micro-services - to scale system
2. Enterprise case study of moving banks to micro-services
3. Common practices to follow in this journey
4. How to build a migration framework
5. Taking advantages of other roles in the migration phase
6. Case study on moving monolith to microservices