Senior Backend Engineer, AI Platform & LLM Infra

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

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.