Senior Backend Engineer

$200,000 – $260,000 + Equity + Benefits + PTO On-site in San Francisco, CA Are you a senior backend engineer who takes pride in building reliable, airtight systems at scale? Do you care deeply about making sure nothing slips through the cracks - that errors are caught, logged, and surfaced rather than silently swallowed, even at a billion requests a month? This is an opportunity to join a fast-growing, profitable startup at the forefront of AI infrastructure, building the compliance and reliability layer that enterprise customers like Adobe, Netflix, and NASA depend on in production. Backed by top-tier investors, the team has built the world’s most widely used LLM Gateway - a unified platform that gives developers secure, scalable access to every major LLM provider. Now, they’re looking for a Senior Backend Engineer to own the guardrails and observability layer that keeps the platform trustworthy at scale. As a senior engineering hire, you’ll take direct ownership of the systems that log, track, and surface everything happening inside the policy enforcement layer. You’ll design CPU-level guardrails to defend against common attacks on LLM APIs, MCP servers, and agents, build out monitoring integrations built for billion-request scale, and ensure that every guardrail call leaves a clear, auditable paper trail. If you’re looking for a role where your engineering depth directly drives enterprise trust and platform reliability, whilst benefiting from strong equity in an already profitable company before they raise their Series A, this is an outstanding opportunity. The Role Own logging and traceability of all guardrail and policy enforcement calls across SpendLogs and relevant database tables Design CPU-level guardrails defending against common attacks on LLM APIs, MCP servers, and agents Eliminate silent failures across guardrail creation, registration, and policy application — with robust error handling and full end-user transparency Build and maintain Datadog, Splunk, Prometheus, and OpenTelemetry integrations Scale observability to 1B+ requests/month with minimal latency overhead and zero memory leaks Collaborate cross-functionally on backend performance, reliability, and security priorities The Person Bachelor’s or Master’s in Computer Science or a related field 2+ years of experience with Python and backend frameworks such as FastAPI or Flask Strong understanding of logging best practices, error handling, and secure backend development Hands‑on experience with monitoring and metrics platforms including Datadog, Splunk, Prometheus, or OpenTelemetry Solid familiarity with PostgreSQL, Redis, or similar databases Driven to deliver high-quality backend code with strong guardrails, auditing, and debugging capabilities Excited to tackle hard bugs and ensure system transparency for end users at enterprise scale #J-18808-Ljbffr