Senior Backend Engineer – AI Platform

About the role

AZX is building an AI platform that provides a governed front‑door to multiple large language models, both hosted and self‑hosted. As a Senior Backend Engineer you will design and operate the core services that power this platform, enabling enterprise customers to track usage, control costs, and enforce policies.

Key responsibilities

• Own the LLM gateway, handling routing, metering, budgeting, guardrails, and adapters for various model providers.
• Develop and maintain the retrieval and knowledge service, including connectors, chunking, hybrid search, reranking, and grounded answers.
• Build an evaluation harness that turns retrieval tuning into evidence with confidence intervals and segment breakdowns.
• Maintain the async framework’s public API, rate‑limit algorithms, and admin tooling, evolving it for durable agent execution.
• Design and enforce authorization across the platform, implementing token hierarchies, capability grammars, and per‑tenant isolation.

Required profile

• 5+ years of production‑grade async Python experience, including cancellation scopes, streaming lifecycles, and connection pooling.
• Deep knowledge of PostgreSQL internals (MVCC, advisory locks, vacuum) and appropriate use of Redis/Dragonfly.
• Proven experience shipping stable API surfaces with versioning, idempotency, error vocabularies, and migration discipline.
• Expertise in at least one LLM‑gateway or retrieval engineering domain, with credibility in the other.
• Cost‑accounting and evaluation‑first mindset, having shipped gates or harnesses that caught regressions.

Required skills

• Python 3.12+ (async, type‑strict), FastAPI/Starlette, Pydantic v2.
• asyncpg, SQLAlchemy, PostgreSQL (including pgvector).
• Redis, Dragonfly, Lua scripting.
• OpenTelemetry, SSE/streaming, OpenAI & Anthropic APIs.
• Job frameworks such as Celery, Dramatiq, Prefect; rate‑limit algorithms (token bucket, GCRA).

What we offer

• Competitive early‑stage startup compensation with equity.
• Bonus eligibility and comprehensive health insurance covering dependents.
• Flexible paid time off and a fully remote work culture.
• Opportunities to work with industry‑leading clients in energy, real‑estate, logistics, and utilities.