- Voice AI that resolves, not transfers.
- Most phone systems trap callers in menus and scripts.
- Vapi is the platform for deploying voice agents that know your business and can listen, adapt, and resolve in minutes.
- The numbers: 1 billion calls. 1 million developers. 10x enterprise ARR growth The customers: Amazon Ring, Service
- Titan, New York Life, Intuit, Kavak, and thousands more, from YC startups to the Fortune 500 The news: a $50M Series B led by Peak XV Partners, with Bessemer Venture Partners, Kleiner Perkins, M12 (Microsoft's Venture Fund), Y Combinator, and our earlier backers.
- Total raised: $72M Why We’re Hiring This Role: The Stream
- Module pipeline
- VAD → STT → LLM → TTS → Transport — runs on cork/uncork backpressure during live phone calls.
- A hundred milliseconds of delay is audible.
- This role owns pipeline stability and pluggability, so the agents and FDE teams can add new models and providers without touching core.
- You’ll consolidate Bull
- MQ into Kafka, harden the provider abstractions (LLM, STT, TTS base classes), instrument the pipeline with event-driven OTEL tracing, and shore up the Postgres SPOFs that contributed to the Oct 15 and Oct 22 incidents.
- What You’ll Do : 30 Day: Ramp on the Stream
- Module pipeline and the cork/uncork backpressure model.
- Walk the Oct 15 / Oct 22 DB incidents and the duplicate-message incident.
- Land a scoped pipeline or provider-abstraction improvement. 60 Day: Own a slice of the Bull
- MQ → Kafka consolidation.
- Ship event-driven OTEL instrumentation for at least one critical pipeline stage.
- Harden one provider plugin path so a new model can be added without core changes. 90 Day: Drive a measurable reliability or latency win on the call path.
- Be the backend owner that agents and FDE teams pull in for design reviews on new providers and pipeline changes.
Who You Are
- Must-haves: You’ve built real-time or streaming systems in production — media pipelines, streaming data, or event-driven backends.
- You’ve debugged a backpressure cascade.
- You have opinions on queue architecture (Bull
- MQ, Kafka, Temporal) and when each is the right fit.
- You’ve built plugin or adapter architectures — extending base classes cleanly, with decoupled implementations.
- You’ve operated Postgres at scale: connection pooling, read replicas, schema migrations (Liquibase or similar). You instrument with Open
- Telemetry and think in event-driven traces, not just logs.
- Nice-to-haves: TypeScript + Node.js + Nest
- JS. The codebase is huge Nest
- JS, but a strong systems-thinking engineer ramps fast — language doesn’t gate the hire.
- Tech stack you’ll work in: Languages: TypeScript on Node.js (primary). Framework: Nest
- JS (large codebase). Pipeline: Stream
- Module (VAD → STT → LLM → TTS → Transport), cork/uncork backpressure.
- Queues: Bull
- MQ (current), Kafka (target — consolidation on roadmap), Temporal.
- Database: Postgres (connection pooling, read replicas), Liquibase for schema migrations.
- Plugin system: provider abstractions
- LLM, STT, TTS base classes (pluggable, decoupled from model integrations). Observability: Open
- Telemetry tracing, event-driven instrumentation.
- Where you likely come from: A streaming or real-time platform (Discord, Slack, Zoom, Twitch, Mux, Live
- Kit), an ML-infra company (Modal, Baseten, Replicate, Together), or a pipeline/workflow shop (Temporal, Stripe Radar, trading systems). Weak fit: backend engineer who’s only built systems where users don’t wait in real time (overnight jobs, reports, dashboards). Why Vapi: Generational impact: Build the human interface for every business Ownership culture : 70% of the company are previous founders Kind team: The founders, Jordan and Nikhil, are Canadians Tier-1 Investors: YC, KP seed, Bessemer Series A, Recent Series B raise
What We Offer
Real stake: We offer a competitive salary and excellent equity ownership Comprehensive health coverage : medical, dental, and vision plans Team love: We love hanging out, and we do quarterly off-sites Flexible time off : take what you need More: catered meals, transportation, gym, and a $10k annual L&D budget
