Cartesia

Software Engineer, Agent Harness

*HQ - San Francisco, CA. Posted 6 months ago

The role

You will build the platform behind Managed Agents. You will own the stack end-to-end to shape latency, reliability, and developer experience for real-time voice agents.

What you will do

  • Evolve the realtime transport layer for audio between users and agents.
  • Trace and cut end-to-end conversational latency across the STT, LLM, and TTS pipeline.
  • Make agent deployments fast and resilient.
  • Define how voice agent quality is measured by building eval suites, LLM-as-judge scoring, and regression tracking.

Required qualifications

  • Experience building and operating distributed backend systems in production.
  • Strong product instincts regarding customer-facing latency, reliability, and developer experience.
  • Fluent use of coding agents.
  • Clear communication with technical and non-technical audiences.
  • Ability to write sharp specs and maintain a presence in design reviews.

Nice to have

  • Experience with real-time media systems in production, including WebRTC, SIP, RTP, or low-latency audio.
  • Experience with voice agents or agent frameworks such as Pipecat, LiveKit, OpenAI Agents SDK, Claude SDK, or Vercel AI SDK.
  • Experience building developer-facing platforms or infrastructure, such as SDK backends or API platforms.
  • Experience with distributed systems at scale, including high-throughput workloads, autoscaling, multi-region architectures, or queue-based systems.

Benefits

  • Competitive base salary
  • Attractive equity package
  • Fully covered medical insurance along with dental and vision for you and your family
  • 9 weeks paternity leave
  • 12 weeks maternity leave
  • 401(k)
  • Monthly commuter allowance
  • Flexible PTO
  • Lunch, dinner and plenty of snacks provided daily
  • Your own personal Yoshi

Before you apply

  • Visa sponsorship is provided and assessed on a case-by-case basis.
  • Cartesia participates in E-Verify and will provide Form I-9 information to confirm employment eligibility after hire.

About the company

Cartesia builds real-time multimodal intelligence through voice models and a production platform. The founding team met as PhDs at the Stanford AI Lab where they invented State Space Models.