Immutable Knowledge Databases - Soares & Nascimento

Darlei Soares and João Nascimento explain how Nubank uses immutable knowledge databases to model and analyze complex microservice interactions.

In this presentation, we explore the concept of knowledge databases, which represent entities and their relationships in a structured and semantic way. By combining this model with immutability—where data is never overwritten, only accumulated—it becomes possible to build systems with a complete, auditable history and native versioning. This approach is particularly powerful in complex ecosystems like Nubank’s, where thousands of microservices interact. We’ll show how modeling these interactions as a knowledge database allows us to uncover patterns, dependencies, and insights that are otherwise hidden, ultimately helping teams understand and evolve the system more safely and intelligently. Biography Darlei Soares and João Nascimento are software engineers and data enthusiasts with deep experience in building systems around immutable knowledge databases. Currently part of the engineering team at Nubank, Darlei and João both work on designing and maintaining highly distributed services that leverage Datomic at scale, powering financial operations for millions of customers. Recorded Nov 13, 2025 at Clojure/Conj 2025 in Charlotte, NC.