Senior Backend Engineer (AI Platform)

Backend EngineerOur 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, energy, logistics, and utilities.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.About the RoleAs 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.Responsibilities:Own the LLM gateway: routing, metering, budgets, guardrail composition, and provider/backend adapters across hosted and self-hosted models.Manage the retrieval and knowledge service: connectors, chunking, hybrid search and reranking, grounded answers, and the MCP surface.Build the eval harness that turns retrieval tuning from judgment into evidence, with confidence intervals and per-segment breakdowns.Own the async framework — its public API, rate-limit algorithms, and admin tooling — and lead its evolution into durable execution for agent runs.Design authorization across the whole surface: token hierarchies, capability grammars, and per-tenant isolation tested as a regression, not asserted in a doc.Own your own definition of done on everything you ship: evals, traces, cost accounting, and the dashboard that would wake you up.Core Qualifications: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 familiarity.Experience shipping API surfaces other engineers build on — versioning, idempotency, error vocabularies, migration discipline, and documentation to match.Depth in at least one of LLM gateway concern (routing, metering, guardrails, provider failover) or retrieval engineering (hybrid search, reranking, eval methodology, audit-ready RAG), with credibility on the other.A cost accounting and evals first mindset — you've shipped a gate or harness that caught a real regression, ideally one of your own.Production 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 rest.Exposure 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.Past work in energy, real estate, utilities, climate or related fields is a plusExperience in both startup and enterprise environments is a plusWhy AZX!Be part of a fast-growing, profitable, mission-driven company with industry-leading clients tackling the massive opportunity of AI transformation in critical industries.Competitive 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 SeattleAdditional Information:Must be willing to travel to Seattle area for final interview and travel 2x/year for company summitsApplicants must be currently authorized to work in the United States on a full-time basis.We are unable to sponsor or take over sponsorship of employment visas at this time.Please only apply to a maximum of 2 roles at a time, any applicants who apply to more then 2 roles within a 6 month period will automatically be disqualifiedNext Steps:If this job sounds like a great fit but don't check ALL of these qualification boxes, we'd still love to hear from you!