Founding AI Engineer

About usCallSphere builds AI voice and chat agents for enterprise B2C operations — HVAC, healthcare, IT support, and logistics. Our agents answer, qualify, schedule, and resolve in 57+ languages, on real phone lines, for companies whose customers call rather than click. We're revenue-generating with paying retainer clients, incorporated in California. This is not a pre-idea startup — it's a working business looking for its second engineer.The roleYou'll be the first engineering hire, working directly with the founder. You'll own entire surfaces of the product rather than tickets: real-time voice pipelines, agent orchestration, the client-facing dashboard, and the infrastructure underneath it. Expect to ship to production in your first week, talk to customers in your first month, and shape what we build in your first quarter.What you'll doBuild and tune real-time voice agent pipelines — ASR, LLM orchestration, TTS, barge-in, latency budgets under 800msDesign multi-agent flows and tool-calling for booking, triage, escalation, and CRM writebackOwn RAG and knowledge pipelines that keep agents accurate on each client's businessBuild and harden telephony integrations (Twilio), webhooks, and client dashboardsSet up evaluation and observability — transcripts, failure analysis, regression suites for agent behaviorTake on infrastructure, deploys, and on-call; we're small and nobody is above the stackWhat we're looking for3+ years shipping production software, with real ownership of something end-to-endStrong Python; comfort in at least one of TypeScript, Node, or GoHands-on LLM application experience — agents, tool use, RAG, prompt and eval work in production, not just prototypesComfort with ambiguity, incomplete specs, and deciding without a committeeBias toward shipping, measuring, and iterating in front of real customersNice to have: real-time audio or streaming systems, telephony (Twilio, SIP, WebRTC), multilingual NLP, AWS, LangGraph or the OpenAI Agents SDK, early-stage startup experience.Tech stackReact · Node/Express · Python AI services · Go gateway · Twilio · AWSWhat we offerMeaningful equity — founding-engineer level, four-year vest with a one-year cliffCompetitive cash relative to a self-funded, revenue-backed startup — we'll be direct about the cash/equity tradeoffDirect customer contact and full ownership of your workNo layers, no roadmap theater, no legacy code to inheritHow to applySend a short note and your GitHub or portfolio to sagar@callsphere.ai. Tell us about one system you built end-to-end and what broke in production.CallSphere Inc. is an equal opportunity employer. All qualified applicants will receive consideration without regard to any legally protected characteristic.