Principal Engineer - Library Architect

Socket.dev; Palo Alto (CA); On-site; USD 180,000 - 240,000; Full time

Job summary

Nubank seeks a Library Architect to own the core programming language ecosystem and shared abstractions powering our backend microservices. This role will oversee, govern, and elevate Nubank's foundational infrastructure architecture.

You will help define the Nubank Way for resilient libraries, ensure stability across thousands of services, and drive cross-language interoperability while mentoring senior engineers and collaborating with executive leadership.

Qualifications

• Deep knowledge to build high-throughput, fault-tolerant backend ecosystems.
• Experience abstracting complex domain logic and standardizing libraries.
• Understanding polyglot architectures and multi-language interfaces.
• Commitment to long-term stability and forward-compatible design.
• Ability to influence senior leadership and drive engineering standards.

Responsibilities

• Define 2–3 year backend language strategy and core libraries.
• Provide horizontal leadership across teams for cross-language patterns.
• Govern an ecosystem of 4,000+ microservices and dependencies.
• Architect AI-ready libraries and developer workflows.
• Lead open-source stewardship and maintain critical libraries.
• Mentor senior engineers and align with executive leadership.

Skills

Deep Systems

Large-scale Abstraction

Cross-Language Proficiency

Stability Focus

Executive Influence

Job description

About Nu

Nu is the leading digital bank in Latin America, serving 135 million customers across Brazil, Mexico, and Colombia. The company has been leading an industry transformation by leveraging data and proprietary technology to develop innovative products and services. Guided by its mission to fight complexity and empower people, Nu caters to customers’ complete financial journey, promoting financial access and advancement with responsible lending and transparency. The company is powered by an efficient and scalable business model that combines low cost to serve with growing returns.Nu’s impact has been recognized in multiple awards, including Time 100 Most Influential Companies, Fast Company’s Most Innovative Companies, and Forbes World’s Best Banks.Visit our Institutional Page

The Opportunity: Building the Bedrock of Nubank's Future

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.

Key Responsibilities & Focus Areas

• Language Landscape Strategy: 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.

• Cross-Language & Ecosystem Architecture: 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.

• Library Governance & Ownership: 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.

• AI-Ready Engineering: Architect foundational libraries, abstractions, and developer workflows optimized for AI-driven development cycles and code generation tools.

• Open Source Stewardship: Lead Nubank’s contributions to and maintenance of critical open-source software libraries and core foundational frameworks.

• Strategic Leadership & Mentorship: 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.

Core Qualifications

• Deep Expertise in Systems: Proven deep knowledge, core competency, and active experience building high-throughput, fault-tolerant backend ecosystems at scale.

• Large-Scale Abstraction Specialist: Demonstrated experience abstracting complex domain logic and standardizing libraries across large-scale distributed architectures (hundreds to thousands of microservices).

• Cross-Language Proficiency: Deep understanding of polyglot architectures, runtime environments, and how core abstractions interface across multiple programming languages.

• Stability Obsessed: Uncompromising belief in high-integrity, forward-compatible software design capable of operating reliably for years without breaking changes.

• Executive & Horizontal Influence: Proven ability to navigate complex organizational structures, partner with senior tech leadership, and drive unified engineering standards across teams facing high delivery pressure.

Why Join Now?

This role reports directly into senior technical leadership. You will have the mandate to fix the foundation of one of the world’s most sophisticated technical environments. We are committed to finding the right structural balance for the world’s top specialized talent.

If you are energized by these challenges and want to work with a world-class, senior team defining the next decade of fintech at scale, ensuring our foundational libraries remain the stable, elegant bedrock of Nubank’s global evolution, this is the place for you!

Our recruitment process may involve the use of artificial intelligence–enabled tools, such as automated interview transcription and analysis, to support the evaluation process. Artificial intelligence is not used to make final hiring decisions; all decisions are made by human reviewers.