Member of Technical Staff, Core Backend

Vapi Technologies Inc.

Job Overview

Location

San Francisco

Job Type

Full-time

Full Job Description

📋 Description

• Own the stability and pluggability of Vapi’s StreamModule pipeline — VAD → STT → LLM → TTS → Transport — which processes live phone calls with sub-100ms latency constraints.
• Consolidate BullMQ messaging infrastructure into Kafka to improve scalability, durability, and operational reliability across the real-time voice agent pipeline.
• Harden provider abstractions (LLM, STT, TTS) using base classes to enable FDE and agent teams to integrate new models and vendors without modifying core pipeline code.
• Instrument the entire call path with event-driven OpenTelemetry tracing to replace log-centric debugging and enable precise latency and failure analysis.
• Resolve Postgres single points of failure (SPOFs) that contributed to production incidents on Oct 15 and Oct 22, including improving connection pooling, read replica usage, and schema migration practices via Liquibase.
• Debug and remediate backpressure cascades in real-time voice systems, ensuring message throughput remains stable under load without audible delays or call drops.
• Drive measurable improvements in pipeline reliability and latency, with clear metrics tied to call success rates and end-user experience.
• Serve as the primary backend owner for design reviews when new providers or pipeline changes are proposed by agent or FDE teams.
• Ramp quickly on the existing NestJS codebase and StreamModule architecture, understanding the cork/uncork backpressure model and its impact on live call flow.
• Ship scoped improvements within 30 days, including a pipeline or provider abstraction enhancement, and own a critical slice of the BullMQ-to-Kafka migration by day 60.
• Ensure all pipeline changes maintain real-time performance guarantees, with zero tolerance for delays that degrade caller experience.
• Collaborate with infrastructure and frontend teams to align on observability standards, schema evolution, and deployment safety for high-throughput voice systems.
• Maintain deep focus on system resilience: anticipate failure modes, design for graceful degradation, and implement automated recovery where possible.
• Work in a production environment handling over 1 billion calls with thousands of enterprise customers including Amazon Ring, ServiceTitan, New York Life, and Intuit.
• Contribute to a codebase built on TypeScript, Node.js, and NestJS, with a strong emphasis on clean plugin architectures and decoupled provider implementations.
• Operate at scale with Postgres databases using Liquibase for schema migrations, read replicas for scaling reads, and connection pooling to prevent overload.
• Participate in incident postmortems and implement preventive measures to avoid recurrence of critical pipeline failures.
• Be the go-to backend engineer for design input on new model integrations, ensuring they adhere to core pipeline constraints and observability standards.

🎯 Requirements

• 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.
• You have experience with TypeScript, Node.js, and NestJS, or are a strong systems-thinking engineer who can ramp quickly on the stack.

🏖️ Benefits

• 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.

Skills & Technologies

JavaScript

TypeScript

Node.js

PostgreSQL

Kafka

Backend

Senior

Onsite

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Vapi Technologies Inc.

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About Vapi Technologies Inc.

Vapi empowers developers to build and deploy advanced voice AI agents through a highly configurable, API-first platform. Serving a wide range of clients from startups to Fortune 500 companies, Vapi simplifies the creation of leading voice AI products and scales phone operations efficiently. The platform supports a global user base, evidenced by its multilingual capabilities in over 100 languages. With impressive traction, Vapi has powered over 300 million calls and launched more than 2.5 million assistants, highlighting its significant impact and reliability in the voice AI market.

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