Senior Backend Engineer at Phonely

You will own the core infrastructure powering real-time voice AI agents that sound indistinguishable from humans. Managing sub-400ms response times at massive scale, you'll design and operate the backend systems handling millions of concurrent conversations. This is a high-ownership role working directly with PhD founders to transform global telecommunications.

• Architect and scale performance-critical backend services using Python (asyncio/FastAPI) and Rust to maintain sub-400ms latency.
• Build and manage the infrastructure required to handle high-concurrency voice traffic and real-time WebSockets across global enterprise customers.
• Collaborate directly with AI research founders to integrate state-of-the-art voice models into a reliable, production-grade distributed system.

• 5+ years of experience building production backend systems, with a proven track record at later-stage (Series B-D) startups during high-growth phases.
• Expert-level proficiency in Python (FastAPI/asyncio) with professional experience or a strong desire to work in Rust for performance-critical paths.
• Deep technical background in real-time systems, including streaming data, telephony protocols, WebSockets, and low-latency processing in AWS/Kubernetes environments.

• Ship code that processes millions of calls monthly for thousands of businesses, experiencing 22% week-over-week growth on a path to 1 billion annual calls.
• Work at the bleeding edge of latency engineering, optimizing real-time streaming and telephony systems where every millisecond directly impacts human-like AI performance.
• Join an elite 8-10 person engineering team in SF immediately following a $16M Series A led by Base10 Partners, offering massive equity upside.