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Senior Backend Engineer (Series A Backed)

Phonely· Engineering
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San Francisco$180k - $230kFull-timePosted 6mo ago

About the role

Senior Backend Engineer role at Phonely (Series A backed) focused on Python-based state systems for real-time voice AI, integrating multiple LLM providers, and building scalable microservices in a fast-paced office in San Francisco.

Responsibilities

  • Build and maintain Python-based state systems that drive what the voice AI says and does across complex, real-time conversations.
  • Integrate and orchestrate multiple LLM providers, including prompt design, tool/function calling, routing, and fallbacks.
  • Write clean, maintainable, high-performance Python code, leveraging asyncio, OOP, and best practices.
  • Write automated tests and validation suites to ensure correctness, resilience, and safe iteration of agent logic and state transitions.
  • Monitor production systems, debug agent behavior, and continuously improve reliability and conversation quality.
  • Implement comprehensive metrics, logging, and alerting to validate correctness, detect failures early, and maintain extremely high availability.
  • Design database schemas, optimize queries, and operate both SQL and NoSQL databases in production.
  • Build and operate authentication and authorization mechanisms with strong security guarantees.
  • Design and build microservices-based architectures.

Qualifications

  • 5+ years writing python, experience writing async web apps using fast api, testing frameworks
  • Understanding of LLMs, APIs, Cloud, CI/CD pipelines
  • Comfortable with understanding technical specifications
  • Understanding of good architecture, security practices
  • Strong technical and communication skills
  • Experience with AWS & Kubernetes

Skills

Required:PythonAsync web frameworks (FastAPI)LLMs integrationCloud & CI/CDAWS & Kubernetes
Last updated Oct 7, 2026. Interested? Apply on the company site.
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About Phonely

AI call centers

Phonely uses existing call recordings to create a 'AI vocal twin' that can answer customer support calls and match or outperform call center agents. On top of that we've built a Zapier like workflow that lets businesses connect to software or transfer calls just like a person would. Our platform sits on proprietary deterministic LLM that is both cheaper and more accurate than gpt-4o for call center inquiries.

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