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Software Engineer, Agent Harness

Cartesia*HQ - San Francisco, CAEngineering
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Salary
$180K - $250K USD
Job type
Full-time
Posted
15 May 2026
Status
Open · checked 7d ago

About this role

Cartesia is hiring a full-time Software Engineer, Agent Harness to join its engineering team in San Francisco, CA. This on-site role is ideal for a distributed systems builder passionate about shaping real-time voice agent infrastructure.

Role Overview

Cartesia builds cutting-edge, real-time multimodal intelligence, focusing on advanced voice models and production platforms. In this position, the engineer drives the platform behind Managed Agents, the company's voice agent product. Responsibilities include owning the entire technology stack to optimize reliability, speed, and overall developer experience for customers deploying production-grade voice solutions.

Key Responsibilities

Improve the real-time transport layer that transmits audio between users and agents across web platforms, SDKs, and telephony without sacrificing quality or speed.
Identify and eliminate bottlenecks across the entire conversational pipeline involving speech-to-text, large language models, and text-to-speech.
Streamline agent deployments for maximum resilience, ensuring rapid cold starts, intelligent scaling, and stability under heavy traffic.
Establish robust evaluation methodologies, including LLM-as-judge scoring and regression tracking, to catch performance and latency drops prior to release.

Requirements

Demonstrated history of building and operating distributed backend systems in live production environments, particularly within high-growth startup settings.
Strong product intuition focused on customer-facing reliability, low latency, and superior developer experience.
Familiarity using coding agents and maintaining alignment with technological advancements.
Excellent communication skills capable of addressing both technical and non-technical stakeholders through detailed specifications and design discussions.

Nice to Have

Production background working with real-time media technologies like WebRTC, SIP, RTP, or low-latency audio.
Exposure to voice agents or frameworks such as Pipecat, LiveKit, OpenAI Agents SDK, Claude SDK, or Vercel AI SDK.
Experience designing developer-oriented infrastructure, API platforms, or SDK backends.
Knowledge of large-scale distributed architectures, multi-region setups, queue-based systems, and high-throughput workloads.

Skills and Tools

Large Language Models (LLM)
Distributed backend systems
Real-time media protocols (WebRTC, SIP, RTP)
Voice agent frameworks

Salary and Benefits

Annual base salary ranging from $180,000 to $250,000 in USD
Attractive equity package
Fully covered medical, dental, and vision insurance for employees and families
9 weeks of paternity leave and 12 weeks of maternity leave
401(k) plan
Monthly commuter allowance
Flexible paid time off policy
Daily provided lunch, dinner, and snacks
Visa sponsorship support evaluated on a case-by-case basis

About the Company

Cartesia creates AI that learns and interacts similarly to humans, originating from research by PhDs at the Stanford AI Lab who invented State Space Models. Backed by investors such as Index Ventures and Lightspeed Venture Partners, the company combines model innovation with systems and product engineering. Cartesia operates an in-person office culture in San Francisco, London, and Bangalore.

How to Apply

To apply for this position, please visit the official Cartesia careers page and submit your application online.

Skills and tech stack

LLM

Questions candidates ask

What is the location of the Software Engineer, Agent Harness role?

The position is based out of the company headquarters in San Francisco, California, as part of an in-office team.

What is the salary range for this position?

The annual base salary ranges from $180,000 to $250,000 USD, accompanied by an equity package.

What qualifications are required for the role?

Candidates need a proven track record of building and running distributed backend systems in production, strong product instincts regarding latency and developer experience, fluency with coding agents, and clear communication abilities.

Does Cartesia offer visa sponsorship?

Yes, visa sponsorship support is available and assessed on a case-by-case basis depending on factors like the specific role and location.

What benefits are provided for US employees?

US employees receive fully covered medical, dental, and vision insurance, parental leave, a 401(k) plan, a monthly commuter allowance, flexible PTO, daily meals and snacks, and competitive equity alongside base salary.

Ready to apply?

The application is on the official Cartesia careers page.

Apply on company site