Senior Backend Engineer — FinTech, Scalable APIs

Watu; United States; Remote; USD 135,000 - 202,000; Full time

Job summary

Watu is seeking a Senior Backend Engineer to own a domain end-to-end within a squad. You will shape the system architecture, write robust Java/Spring Boot code, and raise the quality bar for the team. The role emphasizes distributed systems thinking, clean APIs, and reliable, maintainable services.

You will work in a squad of 4–6, with significant autonomy and responsibility. Design decisions, ADRs, and API docs (OpenAPI) are part of daily work, alongside collaboration with the Tech Lead and

Qualifications

• 5+ years of professional backend software engineering experience.
• 3+ years working in Java in a production environment with design responsibilities.
• Strong Java and Spring Boot depth, including Spring Security and Spring Data.
• REST API design experience (versioning, error handling, pagination).
• Relational database design and query optimization.
• Distributed systems depth with eventual consistency and failure mode design.
• Testing with JUnit/Mockito and integration testing against a real database.

Responsibilities

• Design, build, and maintain backend services and APIs used by other squads and external partners.
• Write unit and integration tests as a first-class part of development.
• Drive architecture discussions within your squad and document ADRs.
• Review pull requests focusing on design, maintainability, performance, and test coverage.
• Write and maintain API specs (OpenAPI) and runbooks for systems you own.
• Contribute to shared libraries and platform standards when relevant across squads.
• Use AI/LLM tooling in daily workflow for code generation, testing, and debugging.

Skills

Java

Spring Boot

Distributed systems

REST API design

JUnit/Mockito

OpenAPI/Swagger

Kafka

AWS

PostgreSQL

Architectural design

Tools

OpenAPI/Swagger

Kafka

PostgreSQL

AWS

Job description

Watu is seeking a Senior Backend Engineer to own a domain end-to-end within a squad. You will shape the system architecture, write robust Java/Spring Boot code, and raise the quality bar for the team. The role emphasizes distributed systems thinking, clean APIs, and reliable, maintainable services.

You will work in a squad of 4–6, with significant autonomy and responsibility. Design decisions, ADRs, and API docs (OpenAPI) are part of daily work, alongside collaboration with the Tech Lead and