Transforming banking for 6 million German customers on AWS with DKB

DKB’s goal is to provide the best customer experience for its 6 million customers, so its digital banking services need to be reliable and highly available. However, the bank was experiencing outages that impacted customer experience, and long release cycles created friction among teams. At the same time, the bank was facing high infrastructure and operational costs.

On a mission to become a tech bank, DKB’s strategy is to build—not buy—and own the differentiating components of its infrastructure. “From a strategic perspective, we needed to have ownership of the core components of our technology,” says Moritz Otte, head of digital products and technology at DKB. “It could be complex and time-consuming to identify the root cause for an incident otherwise.”

Becoming a tech bank also means focusing on the builders to support developer productivity. After gathering feedback from developers and exploring options, DKB selected AWS as its cloud provider. “For us, it was essential to have a cloud provider that was willing to help us evolve in a highly regulated environment,” says Otte. “AWS consistently engaged with our regulatory requirements and supported us in shaping a cloud setup that works for banking.” AWS supports over 143 security standards and compliance certifications globally, including BaFin and Bundesbank—Germany’s financial supervisory authorities. The combination of technical depth and regulatory support made AWS the right choice for DKB’s modernization strategy.

DKB worked alongside AWS Professional Services to plan the banking platform migration, using proven frameworks such as the AWS Migration Acceleration Program (AWS MAP) to accelerate its cloud modernization journey. The bank’s large-scale microservices architecture had complex interdependencies and required a careful approach with full fallback capabilities to avoid downtime. “We didn’t just need minimal downtime and a fast migration,” says Falk Otto, lead project manager and technology lead at DKB. “We also needed to have a rollback plan to facilitate uninterrupted customer access to the banking platform.” DKB adopted a phased migration strategy where selected services that had interdependencies were grouped into the same migration phase, with each service consisting of its own containers and a dedicated database.

AWS provided migration expertise, architectural guidance, and hands-on training so that DKB could have full operational ownership of its infrastructure. AWS Professional Services also brought in Netlight Consulting, an AWS Partner that specializes in migrations and digital transformation. A newly designed operating model together with corresponding runbooks gave DKB full operational ownership of its infrastructure. The cross-functional collaboration among DKB, AWS, and Netlight included sprint-based “migration parties” and hands-on training sessions. “For learning and training, it’s very helpful to have expertise sitting at the table together,” says Otto. “It was great to work alongside AWS and Netlight during the migration and adopt some aspects of the AWS culture.”

To support the replication of millions of documents—for example, bank account statements—from on premises to AWS, the bank used AWS DataSync, a service that simplifies and accelerates secure data migrations. DKB also used AWS Database Migration Service (AWS DMS), which minimizes operational disruption to applications by keeping the on-premises databases fully operational while replicating the data to instances on AWS. DKB implemented a phased cutover strategy to mitigate risk, with database migrations subdivided across five separate overnight windows. To support uninterrupted operations, AWS DMS held the on-premises databases and the AWS databases in sync for several months. This approach proved feasible even for latency-sensitive, customer-facing services like DKB’s internet banking.

The bank migrated more than 100 containerized microservices to Amazon Elastic Kubernetes Service (Amazon EKS), which streamlines Kubernetes operations by automating cluster infrastructure management. It adopted Amazon Relational Database Service (Amazon RDS) for PostgreSQL—simple-to-manage relational databases—for transactional workloads. Bank account statements and other critical documents are stored in Amazon Simple Storage Service (Amazon S3), an object storage service. DKB also adopted several AWS services to support security and compliance, including AWS Backup to centrally manage and automate data protection and AWS Key Management Service (AWS KMS) to create and control keys used to encrypt data. Together, these services created a strong foundation that met DKB’s availability, performance, and regulatory requirements.

As a result of the strategic approach and close collaboration among the teams, the bank completed the migration with no disruption to customers, with near-zero downtime and full fallback capability. In total, DKB migrated 84 databases and 130 APIs containing more than 30 TB of data and over 200 million objects. The bank is now experiencing an up to 100 percent improvement in API response times and a 50 percent reduction in platform and operational costs—and has had no infrastructure-related downtime since the migration.

The migration has resulted in a culture shift, with 25 teams now empowered to manage their own services. “Previously, if there was an issue, teams would create a ticket and wait hours or days for resolution, with a lot of back and forth,” says Jan Klug, technology lead for the banking platform at DKB. “Now, if there is an alert in their monitoring, they can decide how to act on it themselves.” As a result, the resolution time for incidents has decreased by an estimated 25 percent. DKB also uses AWS Enterprise Support for strategic guidance and deep AWS knowledge that adapts to every stage of its cloud journey.

By migrating the entire digital banking platform to AWS, DKB has laid the groundwork for future innovation. The bank estimates a 40 percent reduction in effort for new releases, and the release process itself has been reduced from days to minutes—making it possible to deliver new features to customers faster. DKB can also adopt new technologies faster and is using generative AI to improve the customer experience—for example, with a digital assistant in its banking platform. “Using AWS for building and testing the agent helped us to integrate generative AI capabilities into our systems quickly and in a controlled way,” says Otte. “Our cloud-based development environment significantly reduced the time from experimentation to production.”