Frontend Software Engineer

Frontend Software Engineer - AI Data Platform Company: $80M+ funded, AI data infrastructure Location: On-site, San Francisco, CA (5 days/week in-office) Salary: $175K to $225K + competitive equity Sponsorship: open to visa transfers (OPT, H1B) We're hiring Frontend Software Engineers for a fast-growing, well-funded startup building the data layer for audio AI. The founding team are former engineers and operators from leading AI data companies, and in under two years the company has landed a majority of the largest AI labs and enterprise tech companies as customers, with a waitlist behind them. This isn't a role where you're handed Figma files and asked to convert them. You'll design and build the interfaces that leading AI labs use to make sense of speech and audio data, on top of pipelines already processing terabytes of it daily. The problem you'd help solve: High-quality training data is the current bottleneck for audio AI. Text has largely been solved; audio hasn't. Emotion, tone, pace and accent don't translate cleanly, which makes this a fundamentally harder data problem than the last generation of labeling companies dealt with. Surfacing that complexity in an interface a human can actually reason about is a genuinely hard frontend problem, not a CRUD app. You'd ship polished UI that thousands of users touch daily, build performant interfaces on top of heavy data processing pipelines, expose LLM and DSP-based tooling to customers, and work directly with researchers and operations to turn research hypotheses into deployed data collection interfaces. Real ownership over how it gets built. You'll likely be a fit if you have: 2 to 6 years of frontend software engineering experienceStrong TypeScript and React/Next.js in productionExperience at high-growth, VC-backed startups, not exclusively large or legacy companiesDemonstrated ownership of zero-to-one projects with measurable business impactExperience building performant, data-dense interfaces where responsiveness under load actually mattersA CS degree from a strong program (top ~50 US or equivalent, e.g. Waterloo) Nice to have: Familiarity with TailwindCSS, tRPC, Node.js, PostgreSQL or AWSDomain experience in audio, ML or data infrastructureExperience with real-time data, audio waveform visualisation, or Web Audio APIStrong design sensibility and comfort working from ambiguous specs What you won't find here: This role won't suit you if you've spent your career exclusively at large, slow-moving companies and want a well-defined spec handed to you. The team ships to production daily and you'll be making product and interface decisions the rest of the team builds on. Sponsorship: open to visa transfers (e.g. OPT, H1B). Candidates must be able to work on-site in San Francisco 5 days/week. Seniority Level: Mid-Senior level Skills: ReactNext.jsTypeScriptTailwind CSSNode.jstRPCPostgreSQLAWSFront-End DevelopmentUser Interface Design