Building a Bank (with DDD, Microservices, and Autonomous Teams)

Slides for a talk at FastFlowConf and Agile Meets Architecture 2025

At Upvest, we build the software to manage the investments for millions of people from scratch. And with that, the organization to achieve this. We’d like to tell our story and share our learnings so far.

Being fully aware that, to quote the late Stefan Tilkov, “any particular architecture approach constrains organizational options”, we initially focused on designing an architecture that empowered autonomous product teams, allowing them to operate independently, make domain-driven decisions, and iterate rapidly on their domains.

As the product evolved, we encountered new challenges related to inter-team dependencies and flow efficiency. In response, we reviewed our teams’ topology, and optimized it for improved delivery flow and reducing bottlenecks.

Along with this, we recognized the need to adapt our architectural approach towards a more centralized model. This shift towards an Enabling Team and increased investment in Platform Engineering and DevEx aims to balance the benefits of autonomy with the need for standardized practices and governance in a regulated environment.

In this talk, we’ll share our learnings and strategies for each phase, exploring how we balanced agile principles with evolving architectural needs, and offering insights for teams navigating similar transformations.

Transcript

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2. We make investing as easy as spending money 2017 founded 200 employees €175m funding and more
3. Part I How it started.
4. Retail investing will be a €20tn+ AuM market by 2030 €21.3tn 2030 €13.7tn 2023 Personalised experiences 81% want their investments to match their values Long-term wealth building 77% use investments as a means for saving 3 2 Accessibility 35% of new investors open their account to invest a small amount 1 Sources: ECB, OECD, Statista, Natixis, DIW Econ, Finra Historic 3 year CAGR 14%; Retail investment market in 2018 € 3.8tn
5. Dynamic technology • Highly automated processes • Wide product spectrum Innovative solution approach • Modular systems • All-in-one High scalability across Europe • Multiple country solutions … Upvest investment infrastructure Traditional investment infrastructure… Static technology • Manual processes • Limited product spectrum Outdated solution approach • Long update cycles • Not all-in-one Limited scalability across Europe • Single country solutions
6. “At Upvest we always start with the question: “Why?ˮ. Every engineer first needs to understand the problem we are trying to solve, and why itʼs important to our clients and us. Only once theyʼve done this can they move on to thinking about solutions for the problem. Every engineer needs to have a product mindset. Thatʼs why we call these people Product Engineers.ˮ Juha Ristolainen, CTO
7. Potential domain setup Brokerage Settlement Custody Transaction domain User domain Tax domain Reporting domain Custody domain Shadow accounting Securities accounting Settlement engine Delivery vs. payment Transaction reporting Personal data Compliance data (MiFiD II) Tax Data (FSA etc.) Yearly statements Tax transaction Withholding Tax Calculation 24c KWG Compliance data (MiFiD II) Corporate actions Fulfillment Market data domain Prices data Static data Reg... data Payment domain Trading gateway Saving plans Portfolios Blockorder Internal tooling Use cases domain
8. Event-Driven Microservices
9. Architecture Decision Making 󰠁󰞵󰠁󰢥 󰞵󰲧󰠁󰚐 󰞵󰲧󰠁󰢤 󰲧󰞵󰲧👎 📑 ADR
10. Development Process
11. Go To Market: Set Up For Growth
12. Part II  How itʼs going (as of 2024
13. What kept working -
14. What didnʼt
15. Uneven Domain Evolution
16. Architecture approaches fork
17. Architecture Guild Goals Improve understanding and documentation of shared architecture 02 Provide a forum to discuss and challenge architecture decisions 03 Establish and promote core architecture principles 04 Give everyone interested a chance to learn and to contribute 01 05 Explore and evaluate new technologies
18. Architecture Guild Organization Main forum is guild meetings 02 Staff+ engineers organize and drive 03 Adhere to the existing principles 04 We strive for consensus 01
19. New realities
20. Domain Realignment
21. Domain Realignment 01 Grow teams to more sustainable size 02 More cohesion in teams 03 Narrower structure / fewer tribes Domain B Domain A Domain C 04 Isolate growing domains Domain D
22. What about Collaboration models?
23. Part III  Still Day One 2025
25. Architecture Management
26. Learnings
28. Team Processes • ✅ Guidance and Principle-based governance enables effective work 👉 Add more context at scale • ✅ Use Platform services to guarantee strong compliance • ⏳ Measuring requires common ground
29. Domain-Driven Design • ✅ Instills a good product approach - become a domain expert. • ✅ Service boundaries by business capabilities / value stream make absolute sense. • ⏳ Stable teams only possible to an extend, over time youʼll need to adjust. • ⏳ It will probably get diluted (it got for us) and you have to review every once in a while.
30. Value Streams / Team Topologies • ⏳ Product complexity and startup pace make value-stream analysis difficult 👉 Flow Engineering ideas? • ⏳ Regulatory requirements for Platform require huge team for effective enablement • 🤷 Not everything that should be a platform can be, (yet).
31. Thank you!