Software Engineer, Agent Harness

Job summary

Responsibilities

Cartesia builds real-time multimodal intelligence: fast, state-of-the-art voice models, and the platform that puts them into production. We started as a research lab, pioneered the state space model architecture, and now we're bringing that research to customers through Managed Agents, our voice…

• Evolve the realtime transport layer that carries audio between users and agents, expanding how customers connect across web, SDKs, and telephony without regressing latency or…
• Trace and cut end-to-end conversational latency across the STT, LLM, and TTS pipeline.
• Make agent deployments fast and resilient: faster cold starts, smarter scaling, graceful behavior under load.
• Define how voice agent quality is measured, building eval suites, LLM-as-judge scoring, and regression tracking that catch quality and latency regressions before they ship.

What they're looking for

• Experience building and operating distributed backend systems in production, ideally at a high-growth startup.
• Strong product instincts: you think in customer-facing latency, reliability, and developer experience, and you have opinions on what to build and why.
• Fluent use of coding agents and a habit of keeping pace with the frontier.
• Clear communication with technical and non-technical audiences, sharp specs, and a strong presence in design reviews.

Tech stack

• Databricks