Backend Engineer — AI-Powered Expense Platform

Navan; Greater London; On-site; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Healthcare coverage

Equity plans

Flexible time off

Parental leave

Commuting support

Job summary

Navan is seeking an experienced Expense Engineer to help own the end-to-end expense product across Berlin and London. You will ship backend and frontend features, build AI-backed agents, and improve extraction, policy, and audit capabilities at scale.

The role emphasizes production quality, observability, and cross-team collaboration across time zones. Ideal candidates have 5+ years in production software, strong CS fundamentals, and experience with Java/Spring Boot, TypeScript, or Python

Qualifications

• 5+ years building production software (8+ for Staff).
• Depth in Java/Spring Boot, TypeScript, or Python services.
• Experience with relational data modeling, APIs, and AWS.
• Shipped AI in a real product, including LLM APIs and retrieval.
• Comfort with financial or workflow-heavy domains.

Responsibilities

• Design and ship features in backend services (Java/Spring Boot) and/or web (TypeScript).
• Own APIs and event-driven flows at scale.
• Build or extend LLM-backed agents: tool use, grounding, streaming.
• Improve document extraction and auto-itemization.
• Instrument production with observability and dashboards.
• Collaborate with Product and Design on AI surfaces.
• Review for correctness in financial systems; mentor others.

Job description

Navan is seeking an experienced Expense Engineer to help own the end-to-end expense product across Berlin and London. You will ship backend and frontend features, build AI-backed agents, and improve extraction, policy, and audit capabilities at scale.

The role emphasizes production quality, observability, and cross-team collaboration across time zones. Ideal candidates have 5+ years in production software, strong CS fundamentals, and experience with Java/Spring Boot, TypeScript, or Python