Member of Technical Staff, Core Backend

Vapi

San Francisco, CA

On-site

Who this role is best for

Best suited to senior backend engineers with real-time systems experience working in voice AI or streaming platforms.

Best fit for

Systems engineers who have debugged backpressure cascades in production environments.
— “You’ve debugged a backpressure cascade.”
Developers with strong opinions on queue architecture and plugin systems.
— “You have opinions on queue architecture (BullMQ, Kafka, Temporal)”
Backend owners comfortable with event-driven instrumentation and Postgres at scale.
— “You instrument with OpenTelemetry and think in event-driven traces”

Things to consider

Immediate focus on resolving past incidents and hardening critical pipeline stages.
— “shore up the Postgres SPOFs that contributed to the Oct 15 and Oct 22 incidents.”
Transition from BullMQ to Kafka is a key early deliverable.
— “Own a slice of the BullMQ → Kafka consolidation.”

How to stand out

Detail specific latency wins from past real-time systems projects.
— “Drive a measurable reliability or latency win on the call path.”
Showcase plugin architectures where new models were added without core changes.
— “Harden one provider plugin path so a new model can be added without core changes.”
Highlight Postgres optimization experience, especially around connection pooling.
— “You’ve operated Postgres at scale: connection pooling, read replicas”

Pace · Fast PacedCollaboration · MediumAutonomy · MediumDecision Impact · TeamLevel · Senior

Derived from job-description analysis by Serendipath's career intelligence engine.

What success looks like

Consolidating BullMQ into Kafka
Harden provider abstractions
Instrument the pipeline with event-driven OTEL tracing
Shore up Postgres SPOFs

Typical background

Experience building real-time or streaming systems in production

Skills & requirements

Required

Real-time SystemsStreaming DataEvent-driven BackendsPostgreSQLOpentelemetryQueue ArchitectureProvider AbstractionsSystem InstrumentationPostgres SpofsSchema Migrations

Preferred

TypeScriptNode.jsNestJSBullmqKafkaTemporal

Stack & domain

PostgreSQLLiquibaseOpentelemetryTypeScriptNode.jsNestJSKafkaBullmqTemporalVoice Ai

About the role

Original posting from Vapi via Ashby

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, ServiceTitan, 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 StreamModule 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 BullMQ 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 StreamModule 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 BullMQ → 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 (BullMQ, 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 OpenTelemetry and think in event-driven traces, not just logs.
Nice-to-haves:
TypeScript + Node.js + NestJS. The codebase is huge NestJS, 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: NestJS (large codebase).
Pipeline: StreamModule (VAD → STT → LLM → TTS → Transport), cork/uncork backpressure.
Queues: BullMQ (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: OpenTelemetry tracing, event-driven instrumentation.
Where you likely come from:
A streaming or real-time platform (Discord, Slack, Zoom, Twitch, Mux, LiveKit), 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

Source: Vapi careers (Ashby)