Lead AI Engineer

** Lead AI Engineer** ** Company:** Fluently (<a href="https://getfluently.app/">https://getfluently.app/</a>) **Salary:** $60–180k / year We’re building the world’s best AI Speaking Coach. Our AI listens to your online calls and helps you level up your English. We recently graduated from Y Combinator and raised $2.5M. Over the last 6 months, we’ve grown from $100k to $5M ARR. Our team consists of 7 top-tier professionals (ex-Google, Nvidia, Lyft, Amazon), and both founders have strong technical and research backgrounds. **🔥 Responsibilities** Lead development of our Voice AI Agent (LiveKit) and internal ML toolkit: full ownership of voice/real-time pipelines. occasional backend work. Agents / Runtime: Python, LiveKit/WebRTC, streaming ASR/TTS, VAD, diarization, state machines, session management, retries/timeouts, QoS, latency budgets. Engine / ML: train and deploy models to production (ASR, TTS, VAD, speaker/diarization, embeddings, scoring), classical DSP, ffmpeg/decoding, batch/stream inference, quantization/ONNX/TensorRT, deterministic pipelines, reproducibility. Backend (as needed): Nest.js/Node.js, REST/OpenAPI, Drizzle ORM, Supabase/Postgres (RLS, migrations), external integrations. Applied ML around LLMs: RAG, tool/function-calling, prompt/response routing, safety/guardrails, A/B testing, optimizing quality vs. cost. Design reliable real-time systems: idempotency, backpressure, caching/batching, queues/schedulers, throughput/latency trade-offs. Build data pipelines for models: data collection/cleaning/anonymization, synthetic data, offline/online evaluation, regression testing. Maintain observability/SLOs: Sentry, Prometheus/Grafana/Loki, tracing, alerting. rapid root-cause identification. Infrastructure & deployment: Docker, GitHub Actions, LiveKit Cloud, Modal/Render/AWS, GPU inference, secrets management, rollbacks, canary releases. Ensure quality & simplicity: uv workspaces, ruff/mypy/pytest, pydantic, strict typing. in JS/TS — turborepo, ESLint/Prettier, Zod, internal CLI/integration tools. Documentation, code reviews, OpenAPI, KISS principles. ** 📌 Requirements** Experience in big tech, VC-backed startups, or Yandex. No experience in EPAM, outsourcing agencies, consulting, Web3, or gambling. Open-source contributions: >10 stars on personal repos and >500 contributions in the past year. Active tech blog, Twitter, or Telegram channel. Concrete examples of applications you’ve built or contributed to (links to web, App Store, GitHub, etc.). Any founder experience (even unsuccessful). Good product/design taste and hands-on design experience. Warm recommendations from colleagues or CEOs/CTOs (authentic, not generic LinkedIn quotes). **💼 Conditions** High-velocity execution: the only rule is to consistently ship to production. Daily direct collaboration with the CEO/CTO. You’ll be Engineer #5. Full ownership of projects end-to-end. Competitive salary based on background & capability. 1% equity as a founding engineer. Base salary increases after PMF and successful milestones. Fully async remote — any timezone. Onboarding via Deel in (almost) any country. We do not hire individuals located in Russia. Optional H-1B sponsorship and relocation to the U.S. 1–2 annual offsites — the most recent one was in Bali.