Senior Backend Engineer — AI Voice Agent Platform

Vantaca+HOAi•Redwood City, CA

18h•Remote

About The Position

HOAi is a fast-growing startup revolutionizing the community association management industry. Our AI workforce platform integrates machine learning technology to streamline labor-heavy processes, eliminating inefficiencies and driving scalability. With rapid growth in the AI space, we are pushing boundaries to redefine industry standards. HOAi is the leading AI solution for the community association management industry, enabling organizations to deploy AI Agents that function like experienced managers. These AI Agents go beyond traditional AI by proactively executing complex, multi-step processes with human-like reasoning—working autonomously, 24/7, across your entire operation. This transformation optimizes labor costs, enables growth without additional hires, and ensures faster, higher-quality service for residents and board members. HOAi was acquired by Vantaca in the fall of 2024. Vantaca just achieved unicorn status with a $1.25B valuation, so it's safe to say we're past the "scrappy startup phase." We're not just building a successful company – we're building the category-defining platform that will transform how an entire industry operates. Here's the reality of our trajectory: Growing 100% year-over-year Our AI product (HOAi) went from $0 to millions in months Backed by Cove Hill Partners and JMI Private Equity 6M+ doors on our platform, displacing legacy systems About the role We’re building a production-grade AI voice agent platform that supports real-time, low-latency conversations at scale. The backend powers session orchestration, streaming pipelines, tool execution, integrations, and the data layer that makes voice agents reliable, debuggable, and continuously improving. This role is for someone who can ship quickly while maintaining a high bar for correctness, observability, and uptime in real-time systems.

Requirements

6+ years backend engineering experience with ownership of production systems.
Strong distributed systems fundamentals, including queues/workers, caching, and operational best practices.
Excellent data modeling and API design skills (versioning, contracts, idempotency).
Comfortable in a high-velocity environment; pragmatic, curious, and outcome-oriented.
Experience building or operating low-latency systems (real-time streaming, WebSockets, RTC, event-driven architectures).

Nice To Haves

Voice/real-time experience: WebRTC/RTC providers, telephony, streaming audio, SIP concepts, jitter/packet loss mitigation.
LLM and agent architecture experience: tool calling, planning/execution loops, memory/state, eval harnesses.
Familiarity with SDKs/frameworks: LiveKit, Twilio/telephony stacks, Vercel AI SDK, LangChain/LangGraph, Anthropic Agents SDK.
Experience with observability for real-time systems (OpenTelemetry traces spanning streaming + async workflows).

Responsibilities

Own voice agent backend services: session lifecycle, call routing, participant management, conversation state, and real-time orchestration.
Build streaming pipelines: integrate and operate STT/TTS and real-time model endpoints; manage latency budgets, backpressure, and jitter.
Agent runtime + tools: implement tool calling, sandboxed execution, retries/idempotency, rate limits, and per-tenant budgets/quotas.
Integrations: telephony/RTC providers, calendars/CRMs/support tools, webhooks, and event streams; build durable sync adapters.
Data platform: model and store transcripts, audio metadata, agent actions, outcomes, evaluations, and audit trails; optimize for query + replay.
Reliability engineering: SLIs/SLOs, incident response, end-to-end tracing across streaming + tool calls, and automated degradation strategies.
Security and privacy: secrets management, least privilege, encryption, data retention controls, PII redaction, and tenant isolation.

Benefits

Our eNPS is +68! (Google it, that is great).
Benefits: Medical, Dental, and Vision kick in day one.
Unlimited PTO (with a requirement for employees to take a minimum of one continuous week per year).
401K with Company Match.
Remote Flexible - come to the office when needed.
Great parental leave benefits.
Named on Inc 5000 list of America’s Fastest Growing Private Companies.
Named on Inc 5000 Vet 100 Private Companies list multiple years in a row.
Winner of Coastal Entrepreneur Award, Technology Category.
Active employee-led Culture Committee.
Ongoing industry and professional development trainings available to all employees.
Multiple leaders on the executive committee recognized as 40 under 40 recipients for contributions to business and community.
We’re playing offense to win! Our product market fit and our world-class employees make us the leader in our space. We’re building something cool and people like it here.