{"id":4407,"url":"https://alion.io/job/cartesia-software-engineer-agents","title":"Software Engineer, Agent Harness","company":{"id":1846,"name":"Cartesia","domain":"cartesia.ai","url":"https://alion.io/company/cartesia","size_band":"501-1000","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"A","score":91,"open_postings":27,"ghost_share":0.074,"stale_share":0,"repost_share":0,"time_to_fill_p50_days":170,"computed_at":"2026-10-16T05:45:00Z"}},"role":"Backend","role_family":"Backend","seniority":null,"employment_type":"full_time","work_mode":"on_site","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["San Francisco, United States"],"countries":["US"],"hiring_countries":[],"hiring_countries_total":0,"salary":{"min":180000,"max":250000,"currency":"USD","period":"year","gross":null,"usd_annual":250000},"salary_estimate":null,"experience_years_min":null,"visa_sponsorship":true,"relocation_package":false,"has_equity":true,"technologies":[{"name":"Databricks","optional":false},{"name":"LLM","optional":false},{"name":"Multimodal AI","optional":false},{"name":"Text-to-Speech","optional":false},{"name":"Voice Agents","optional":false},{"name":"Claude","optional":true},{"name":"LiveKit","optional":true},{"name":"OpenAI Agents SDK","optional":true},{"name":"Vercel AI SDK","optional":true},{"name":"WebRTC","optional":true}],"status":"live","first_seen_at":"2026-05-15T20:54:31Z","employer_posted_date":"2026-05-15","last_verified_at":"2026-10-16T23:59:49Z","board_verified":true,"closed_at":null,"days_open":154,"trust":{"level":"ok","repost_count":0,"flags":["company_stale"],"days_open":153},"description":"About Cartesia\nOur mission is to architect AI that learns from and interacts with the world like humans do.\nWe're pioneering the model architectures that will make this possible. Our founding team met as PhDs at the Stanford AI Lab, where we invented State Space Models or SSMs, a new primitive for training efficient, large-scale foundation models. Our team combines deep expertise in model innovation and systems engineering paired with a design-minded product engineering team to build and ship cutting edge models and experiences.\nWe're funded by leading investors at Index Ventures and Lightspeed Venture Partners, along with Factory, Conviction, A Star, General Catalyst, SV Angel, Databricks and others. We're fortunate to have the support of many amazing advisors, and 90+ angels across many industries, including the world's foremost experts in AI.\nAbout the Role\nCartesia 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 agents product.\nIn this role, you'll build the platform behind Managed Agents. Customers rely on our stack to run real-time, production-grade voice agents. You'll own the stack end-to-end and directly shape the latency, reliability, and developer experience of every agent built on Cartesia.\nYour Impact\nEvolve the realtime transport layer that carries audio between users and agents, expanding how customers connect across web, SDKs, and telephony without regressing latency or quality.\n\nTrace and cut end-to-end conversational latency across the STT, LLM, and TTS pipeline.\n\nMake agent deployments fast and resilient: faster cold starts, smarter scaling, graceful behavior under load.\n\nDefine 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.\n\nWhat You Bring\nExperience building and operating distributed backend systems in production, ideally at a high-growth startup. We care more about what you've shipped than strict years of experience.\n\nStrong product instincts: you think in customer-facing latency, reliability, and developer experience, and you have opinions on what to build and why.\n\nFluent use of coding agents and a habit of keeping pace with the frontier.\n\nClear communication with technical and non-technical audiences, sharp specs, and a strong presence in design reviews.\n\nNice-To-Haves\nExperience with real-time media systems in production, including WebRTC, SIP, RTP, or low-latency audio.\n\nExperience with voice agents or agent frameworks such as Pipecat, LiveKit, OpenAI Agents SDK, Claude SDK, or Vercel AI SDK.\n\nExperience building developer-facing platforms or infrastructure, such as SDK backends or API platforms.\n\nExperience with distributed systems at scale, including high-throughput workloads, autoscaling, multi-region architectures, or queue-based systems.\n\nNote: Cartesia participates in E-Verify and will provide the federal government with Form I-9 information to confirm employment eligibility after hire.\nMore Details\nIn-office policy: We’re an in-person team based out of offices in San Francisco, London and Bangalore. We love being in the office, hanging out together, and learning from each other every day.\nVisa sponsorship: We provide visa sponsorship support and assess each circumstance on a case-by-case basis. However, visa sponsorship is dependent on many factors, including the role you are applying for, and the location you are going to be based, and so we can't always guarantee success. Your Recruiter will work with you to understand your visa sponsorship needs from the first call.\nWe ship fast. All of our work is novel and cutting edge, and execution speed is paramount. We have a high bar, and we don’t sacrifice quality or design along the way.\nWe support each other. We have an open & inclusive culture that’s focused on giving everyone the resources they need to succeed.\nOur Benefits (US Employees Only)\nCompensation Competitive base salary alongside attractive equity package.\nHealth Insurance Fully covered medical insurance along with dental and vision for you and your family.\nParental Leave 9 weeks paternity & 12 weeks maternity leave\n401(k)\nCommuter Allowance A monthly stipend to help you get to and from the office.\nFlexible PTO Take as much time as you need to recharge your batteries.\nMeals & Snacks Lunch, dinner and plenty of snacks, provided daily.\nYour own personal Yoshi\nOur Commitment to Equal Opportunity\nCartesia is an equal opportunity employer. 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