Senior Backend Engineer (Python)

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Title of the role: Senior Backend Engineer (Python)

Location: San Francisco, CA

Company Stage of Funding: Seed / Early-Stage (YC-backed)

Office Type: Onsite – 5 Days a Week

Salary: $150,000 – $220,000 Equity (0.10% – 0.45%)

Company Description

We’re representing a fast-growing, YC-backed startup building the infrastructure for AI-powered voice agents. Their platform enables companies—especially large contact centers—to build, simulate, and deploy voice AI systems that handle customer support at scale.

The company is growing rapidly, with strong early traction and partnerships with some of the largest contact centers globally. Their mission is to power the future of business communication, where AI agents handle the majority of customer interactions.

What You Will Do

As a Senior Backend Engineer, you will build and scale the systems that power real-time voice AI agents operating in production environments.

You will:

• Build and maintain Python-based state systems that control real-time conversational behavior.
• Design and orchestrate integrations with multiple LLM providers, including prompt design, routing, and fallback logic.
• Develop high-performance backend services using async Python (e.g., FastAPI).
• Write automated tests and validation systems to ensure correctness and reliability of agent behavior.
• Monitor production systems, debug issues, and continuously improve system reliability and conversation quality.
• Implement metrics, logging, and alerting systems to ensure high availability.
• Design and optimize database schemas across SQL and NoSQL systems.
• Build secure authentication and authorization systems.
• Architect and maintain microservices-based systems.

This role is highly hands-on and requires building production systems that operate in real-time, high-throughput environments.

Ideal Background

The ideal candidate is a strong backend engineer with deep Python expertise and experience building scalable, production-grade systems.

• 5 years of experience writing production Python code.
• Experience building async web applications (e.g., FastAPI).
• Strong understanding of system design, architecture, and backend best practices.
• Experience working with LLMs, APIs, and cloud infrastructure.
• Experience with CI/CD pipelines and testing frameworks.
• Strong understanding of security and authentication systems.
• Experience with AWS and Kubernetes.
• Strong communication skills and ability to collaborate cross-functionally.
• Comfortable working in a fast-paced, high-intensity startup environment.

Preferred

• Experience building real-time systems (e.g., voice, streaming, or event-driven architectures).
• Experience with telephony systems (SIP, voice APIs).
• Experience with Redis and distributed systems.
• Experience with observability tools (Datadog, logging, tracing).
• Familiarity with modern frontend frameworks (Next.js) for full-stack collaboration.

Compensation and Benefits

• Salary: $150,000 – $220,000 base.
• Equity: 0.10% – 0.45%.
• Work Model: Fully onsite in San Francisco (5 days/week).
• Visa: U.S. work authorization required.

Team & Culture:

• Highly driven, builder-oriented team with a strong ownership mindset.
• Collaborative, in-person culture with shared meals and team activities.
• Regular team offsites and travel opportunities.

Impact:

• Work on core infrastructure powering real-time AI voice systems used by large enterprises.
• Direct influence on product direction and system architecture at an early-stage company.