Senior Backend Engineer (AI Platform)

Job DescriptionJob DescriptionSenior Backend Engineer (AI Platform) AZX | Remote (U.S.) | Full time | Applications close November 12Compensation: $140,000 - $230,000, plus bonus eligibility and equityAs a Backend Engineer you will build the services our products and client solutions run on. The center of gravity is LLM infrastructure: the layer that puts one governed front door over many models, hosted and self-hosted, and answers the questions enterprises actually ask: who used which model, for what, at what cost, under whose rules. The platform's first customers are our own client-facing engineers, the people delivering client outcomes with what you build, so requirements arrive concrete, feedback arrives same-day, and the people you support are in the same meeting. About AZX Our mission is to accelerate positive impact in critical industries through AI transformation. We specialize in physics-informed ML and enterprise AI solutions that directly address climate and sustainability challenges.We're growing quickly and already work with category leaders in real estate (CBRE), energy (LevelTen Energy), logistics (Flexe), and utilities.We're a public benefit corporation, founded in 2024, and have been profitable from inception.We work on challenges in clean energy, decarbonization, climate risk, energy systems, and global economics. We're building our company for long-term success and aim to create the ultimate place to work for those passionate about AI and making a positive impact. What You'll Work On Own the LLM gateway: routing, metering, budgets, guardrail composition, and provider/backend adapters across hosted and self-hosted modelsManage the retrieval and knowledge service: connectors, chunking, hybrid search and reranking, grounded answers, and the MCP surfaceBuild the eval harness that turns retrieval tuning from judgment into evidence, with confidence intervals and per-segment breakdownsOwn the async framework (its public API, rate-limit algorithms, and admin tooling) and lead its evolution into durable execution for agent runsDesign authorization across the whole surface: token hierarchies, capability grammars, and per-tenant isolation tested as a regression, not asserted in a docOwn your own definition of done on everything you ship: evals, traces, cost accounting, and the dashboard that would wake you up What We're Looking For If this job sounds like a great fit but you don't check all of these boxes, we'd still love to hear from you.5+ years of deep, production async Python: cancellation scopes, streaming lifecycle, and connection poolingPostgres as infrastructure: comfortable reasoning about MVCC, advisory locks, and vacuum discipline, with Redis/Dragonfly used (and not used) where it belongs; real distributed-systems experience, not just familiarityExperience shipping API surfaces other engineers build on: versioning, idempotency, error vocabularies, migration discipline, and documentation to matchDepth in at least one of LLM gateway concerns (routing, metering, guardrails, provider failover) or retrieval engineering (hybrid search, reranking, eval methodology, audit-ready RAG), with credibility on the otherA cost accounting and evals first mindset: you've shipped a gate or harness that caught a real regression, ideally one of your ownProduction depth in some modern stack, and the aptitude to ramp quickly on unfamiliar toolsPractical familiarity with our core stack: Python 3.12+ (async, type-strict, FastAPI/Starlette, Pydantic v2), asyncpg/SQLAlchemy, Postgres (incl. pgvector), and Redis/Dragonfly with Lua, with willingness to research into the restExposure to the surrounding ecosystem: OpenTelemetry (incl. GenAI conventions), SSE/streaming lifecycles, OpenAI/Anthropic provider APIs, job frameworks (Celery/Dramatiq/Prefect-class), rate-limit algorithms (token bucket, GCRA), and integer-cents money handling Nice to Have Past work in energy, real estate, utilities, climate, or related fieldsExperience in both startup and enterprise environments Location This role is fully remote within the U.S., with a cluster of teammates in Seattle. You'll travel to the Seattle area for your final interview and twice a year for company summits. Candidates must be currently authorized to work in the U.S. on a full-time basis. AZX is unable to sponsor or take over sponsorship of employment visas at this time. Hiring Process Provn is our hiring partner.Please apply to no more than two AZX roles at a time. Anyone who applies to more than two roles within a six-month period will be automatically disqualified.Provn is your proof layer for getting hired. Builders complete challenges for AI-transformed roles to show AI fluency and showcase critical skill requirements. Hiring managers and recruiters are saying that candidate video presentations are more helpful than referrals for selecting their interview loops. Benefits & Perks Be part of a fast-growing, profitable, mission-driven company with industry-leading clients tackling the massive opportunity of AI transformation in critical industriesCompetitive early-stage startup compensation (based on capabilities, experience, and location)Bonus eligibilityHealth insurance with meaningful coverage for dependentsFlexible paid time offEquityFully remote culture with a cluster of teammates in SeattleAZX is an equal opportunity employer. We are committed to building a diverse and inclusive team and do not discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity or expression, national origin, age, disability, veteran status, or any other characteristic protected by applicable law.