Backend Engineer, Test

At Nucleus, we build intelligent systems that depend on backend infrastructure being correct, reliable, and resilient under real-world conditions. High-quality backend services are not just support systems here-they are part of the foundation that makes advanced AI products trustworthy at scale.

Role overview

We’re hiring a Backend Test Engineer to help raise the quality bar across our APIs, micro-services, and data-intensive backend systems. This is an SDET-style role for someone with 2-3 years of experience who wants to work deeply on backend quality through automation, systems thinking, and close collaboration with engineering-not frontend or mobile testing.

What you’ll do

• Design, implement, and maintain automated tests for backend services, REST APIs, and micro-services across functional, integration, and regression layers
• Build or extend test automation frameworks using a modern language such as Python, TypeScript, or Java, and integrate them into CI/CD pipelines
• Perform exploratory API testing using tools like Postman or similar, alongside automated API testing with frameworks such as pytest, Playwright API, RestAssured, or equivalent tools
• Partner closely with backend engineers to define test strategies, review requirements, and improve service testability, observability, and robustness
• Validate data-heavy backend workflows, including service-to-service interactions, database-facing logic, and failure scenarios
• Contribute to non-functional testing where relevant, including performance, load, and basic resilience testing using tools such as JMeter, Locust, k6, or similar
• Improve release confidence by maintaining test data, triaging failures, debugging flaky tests, and helping teams identify root causes quickly
• Support a strong quality culture by improving coverage, documenting gaps, and helping ensure stable, reliable releases

What we’re looking for

• 2-3 years of experience as a backend QA engineer, SDET, or test engineer working primarily on APIs, backend systems, or micro-services.
• Strong understanding of backend fundamentals, including REST APIs, HTTP, JSON, databases, and client-server architecture
• Hands-on experience with at least one programming language used for test automation, such as Python, Java, or JavaScript/TypeScript
• Experience writing and maintaining automated API tests and integrating them into CI/CD workflows using tools such as GitHub Actions, GitLab CI, or Jenkins
• Familiarity with test management and bug-tracking tools, and comfort working with logs, metrics, and service-level diagnostics to investigate failures
• Practical experience testing distributed systems or microservices, including integration points and edge cases across services
• A thoughtful quality mindset, with strong attention to detail and the ability to reason clearly about failure modes, data integrity, and regression risk
• A collaborative working style and the ability to partner effectively with backend engineers, product teams, and other stakeholders

Why Nucleus

At Nucleus, test engineers play a meaningful role in shaping the quality of systems that power advanced AI products and infrastructure. You’ll work with modern tooling, strong engineers, and a team that values deep backend testing, thoughtful automation, and real ownership—not manual-only execution at the edge of the process.

If you care about building confidence into complex systems and want your work to directly influence the reliability of AI products at their foundation, we’d love to hear from you.