Senior Backend Engineer (AI Platform)

AZX; Seattle, Northern (WA, KY); Hybrid; USD 140,000 - 230,000; Full time

Benefits offered by this job

Health insurance

Equity

Fully remote culture

Stock options

401k

Job summary

AZX seeks a Backend Engineer to build the LLM infrastructure powering client solutions. You will design an API-backed platform to route, meter, and govern models, hosted or self-hosted, prioritizing cost and governance.

You will collaborate with client engineers, ship reliable systems with fast feedback, and help scale our remote-first company with a Seattle cluster, equity, health coverage, and ongoing learning opportunities.

Qualifications

• 5+ years of production async Python experience.
• Distributed-systems with Postgres and Redis/Dragonfly experience.
• Experience shipping API surfaces with versioning and error vocabularies.
• Depth in LLM gateway or retrieval engineering with credible other side.
• Cost accounting and evals mindset; shipped a gate or harness that caught regressions.

Responsibilities

• Own the LLM gateway: routing, metering, budgets, guardrails, adapters across models.
• Manage retrieval and knowledge service: connectors, chunking, hybrid search, reranking, grounded answers.
• Build eval harness for retrieval tuning with confidence intervals and breakdowns.
• Own the async framework, API, rate-limiting, and admin tooling for durable execution.
• Design authorization across the surface: token hierarchies, per-tenant isolation tests.
• Own definition of done: evals, traces, cost, and a dashboard.

Skills

Async Python

Postgres MVCC

API design

LLM gateway

Retrieval engineering

Cost accounting

OpenTelemetry

Python frameworks

Lua

Tools

FastAPI

SQLAlchemy

Postgres

pgvector

Lua

Job description

Our mission is to accelerate positive impact in critical industries through AI transformation.

We’re a public benefit corporation , founded in 2024. We bootstrapped profitably for our first year and are now backed by leading investors focused on AI, climate and energy.

We’re growing quickly and already work with category-leaders in real estate (CBRE), energy (Franklin Energy), logistics (Flexe) and power utilities such as Puget Sound Energy and others.

We're built on three simple ideas:

• We're at the intersection of two massive transformations: AI and climate change.
• AItechnology is far outpacing critical industry's ability to harness it.
• The most impactful opportunities are often in messy business processes.

To tackle this, we've put together a different kind of company. We're not a SaaS company, nor a typical consultancy.

Instead we're focused on client problems and impact. We create solutions that combine consulting, custom engineering and reusable approaches (data, code, models...).

AZX is led by experienced founders from AI and climate focused companies.

Working at AZX

We hope AZXis the best career step you ever take. We're aiming to build the kind of company we dreamed of:positive impact, fun, interesting problems, enjoyable colleagues (high EQ, low drama), flexible work-life and built to last.

While we're an early-stage startup, we do offer:

• Competitive compensation for our stage of company, including base and bonus
• Healthcare with meaningful coverage for dependents and HSA
• Flexible time off
• Stock equity
• 401k
• Fully remote culture with a cluster of colleagues in Seattle
• Twice-yearly immersive in-person summits as well as training opportunities

As we grow, we'll continue to add new benefits (though if you're driven by perks, you might be happier at big tech).

It's just the beginning for AZX. If you're motivated by positive impact through technology, please reach out to us. We'd love to build this with you and have you share in the experience and upside.

Location

United States

Employment Type

Full time

Location Type

Remote

Compensation

We offer competitive early-stage startup compensation based on your capabilities, experience, and location.

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.

About the Role

As 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 pooling
• Postgres 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 tools
• Practical 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 plus
• Experience in both startup and enterprise environments is a plus

Why 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)

Health insurance with meaningful coverage for dependents

Flexible paid time off

Equity

Fully remote culture with a cluster of teammates in Seattle

Additional Information

Must be willing to travel to Seattle area for final interview and travel 2x/year for company summits

Applicants 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.

Compensation Range: $140K - $230K