Senior Full-Stack Software Engineer

About Keo

Keo is a B2B fintech building the credit, card, and payment infrastructure that businesses across Latin America and Canada run on. Our platform issues corporate cards, underwrites and services credit lines, moves money across banking rails, and settles on blockchain rails, in production and across multiple countries.

Engineering owns real financial flows end to end. We run a distributed microservices platform on Google Cloud, we are scaling fast into new markets, and we are investing heavily in reliability, security, and engineering craft. If you want to own systems where correctness moves money, this is that place.

The position

You will design, build, and own the backend services that sit directly in the money path: credit lines, loans, card issuing, payments, and settlement rails. You work across the full stack, but your center of gravity is the backend: distributed systems, event-driven architecture, data modeling, and correctness under financial and regulatory constraints. This is a high-bar role, we expect strong system design, operational ownership, and the judgment to raise the reliability and security bar of the platform.

Responsabilities

• Own money-path services. Design, build, and operate Node.js and TypeScript microservices that run real financial flows: credit, loans, card issuing, payments, and rails;
• Work event-driven. Publish and consume domain events over Cloud Pub/Sub, orchestrate multi-system sagas, and guarantee idempotency and correctness under CQRS;
• Model financial data. Design transactional schemas in PostgreSQL and read models for query and reporting in BigQuery;
• Build integrations. Own adapters to card processors, banks, KYC providers, and open-banking counterparts behind clean, testable boundaries;
• Power decisioning. Extend the parametrized rule engines that drive underwriting and financial calculations;
• Raise reliability. Bring testing to the money path, plus observability (APM, structured logging), SLOs, and incident readiness;
• Engineer for compliance. Treat PCI-DSS, SOX, and SOC 2 as design inputs: secrets management, authentication, least privilege, auditability;
• Ship full-stack. Drop into the React and TypeScript frontend when a feature needs to land end to end;
• Lead and mentor. Own technical design, review code, and grow engineers across squads and countries.

Qualifications/Required Experience

• 6+ years building and operating backend services in production, with deep Node.js and TypeScript expertise;
• Strong distributed-systems fundamentals: microservices, event-driven architecture, messaging, idempotency, and consistency trade-offs;
• Solid data modeling and SQL (PostgreSQL); comfortable with ORMs and migrations;
• Proven API design (REST and GraphQL) and integration engineering against third-party systems;
• Rigorous engineering discipline: automated testing, observability, and secure coding, especially on critical paths;
• Cloud-native experience, ideally on Google Cloud Platform;
• Genuine full-stack range: able to build a feature end to end, including a React / TypeScript UI;
• Technical leadership: system design, code review, and mentoring;
• Comfortable working in English and Portuguese, async and distributed.

Nice to have

• Fintech, payments, or another regulated domain (PCI-DSS, SOX, SOC 2, KYC / AML);
• Google Cloud and event-driven architectures (Pub/Sub, CQRS);
• Decisioning and rule engines, financial calculations, or underwriting systems;
• Event sourcing / CQRS at scale, and workflow or saga orchestration (xstate or similar);
• Terraform / IaC and Azure DevOps pipelines;
• Blockchain or payment-rails exposure (Algorand, stablecoins, settlement).