Principal Engineer - Library Architect

Nubank•Palo Alto, CA

2d•Hybrid

About The Position

Nubank was built on bold technical choices: emphasizing simplicity, immutability, and state-of-the-art concurrency as the foundation for a global financial revolution. Today, as we scale to serve our customers globally and enter a new era of AI-driven engineering, we are doubling down on our commitment to foundational technical excellence. As a Library Architect, you will take ownership of the core programming language ecosystem and shared abstractions that power our backend microservices. This role will oversee, govern, and elevate Nubank's foundational infrastructure architecture. You will help define the "Nubank Way" of building resilient core software libraries and oversee how they interact across the bank's broader programming language landscape. You will ensure that our internal libraries—which support 4,000+ microservices—are stable, idiomatic, and maintained to the highest standards.

Requirements

Proven deep knowledge, core competency, and active experience building high-throughput, fault-tolerant backend ecosystems at scale.
Demonstrated experience abstracting complex domain logic and standardizing libraries across large-scale distributed architectures (hundreds to thousands of microservices).
Deep understanding of polyglot architectures, runtime environments, and how core abstractions interface across multiple programming languages.
Uncompromising belief in high-integrity, forward-compatible software design capable of operating reliably for years without breaking changes.
Proven ability to navigate complex organizational structures, partner with senior tech leadership, and drive unified engineering standards across teams facing high delivery pressure.

Responsibilities

Define the 2–3 year technical direction for backend language adoption and core libraries at Nubank. Guide the evolution of supported languages and idiomatic patterns across the bank, driving migration away from legacy tooling and anti-patterns.
Provide horizontal leadership across engineering teams and tech stacks. Design and evaluate cross-language library capabilities and architecture patterns to ensure seamless interoperability across the bank’s language landscape.
Solve core library ownership challenges by rationalizing an ecosystem of 4,000+ microservices and dependencies. Prevent uncoordinated breaking changes and establish active stewardship for shared foundational components.
Architect foundational libraries, abstractions, and developer workflows optimized for AI-driven development cycles and code generation tools.
Lead Nubank’s contributions to and maintenance of critical open-source software libraries and core foundational frameworks.
Act as a technical counterweight to product teams to safeguard foundational stability, security, and long-term reusability. Mentor senior engineers and influence General Managers and Engineering Directors.