Senior Backend Engineer (Python)

We’re building the future of voice AI for businesses, with a platform designed to make real-time agents easy to build, tune, and operate.

We’re looking for a senior backend engineer to work on core systems that drive live voice conversations in production. This is a hands-on role with a lot of ownership and a lot of Python.

What you’ll do

• Build Python-based state systems for real-time voice AI conversations
• Integrate multiple LLM providers (prompting, routing, tool calling, fallbacks)
• Write high-performance async Python (FastAPI, asyncio)
• Design and test resilient agent logic and microservices
• Operate and improve production systems with strong observability

What we’re looking for

• 5+ years of Python experience, including async web services
• Experience with FastAPI, testing, and CI/CD
• Strong system design and security fundamentals
• Familiarity with LLMs, cloud infrastructure, AWS, and Kubernetes

Stack

Python, FastAPI, async microservices, AWS/GCP, Kubernetes, Redis, Firebase, Supabase, Datadog, SIP/voice APIs

Why Phonely

Small, intense team of builders. High ownership, fast pace, real impact. In-office 5 days/week in SF. Company-paid meals, great culture and periodic international work trips.