Senior Backend Engineer (Python)

About the role

At some point in the future, every business will answer their phone with voice AI. We are making sure that when they build that AI agent, the experience of doing so doesn’t suck.

We’re growing incredibly fast and need someone who thrives in a dynamic, high-pressure environment to work in our engineering. This role is critical to the success of our company. We’re looking for someone who is roll up their sleeves and dig in, and double down when things get tough.

We’re looking for someone who is highly technical, driven, and fun to work with. You’ll be working directly with our engineers, customers support team, and product team.

NOTE: This is an engineering position. You will be writing code, a lot of it and it will be a lot of work… if you’re looking for a cushy corporate job where nothing get done, I recommend checking out some of our competitors. If you’re looking to be a part of a winning team and to make a real difference read on. This role is in office 5 days a week in San Francisco.

Your day to day:

- 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.

- Desgin 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

Our Software Stack:

- Backend: Python, microservices, async programming

- Cloud & Infrastructure: AWS, GCP, Kubernetes, Redis

- Databases: Firebase, Supabase

- Frontend: Next.js

- Observability & Monitoring: Datadog, logging, metrics, tracing

- Telephony & Voice AI: SIP, voice APIs, real-time call handling

- Other tools & practices: CI/CD, automated testing, resilient architecture