Senior Backend Engineer — AI Voice Agent Platform

Senior Backend Engineer — AI Voice Agent Platform

Redwood City, CA
• Hybrid
• Full-time

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

We’re building a production-grade AI voice agent platform that supports real-time, low-latency conversations  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.

• 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, back pressure, 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.

• 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, Web Sockets, RTC, event-driven architectures).

• 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:
  Live Kit, Twilio/telephony stacks, Vercel AI SDK, Lang Chain/Lang Graph, Anthropic Agents SDK.
• Experience with observability for real-time systems (Open Telemetry traces spanning streaming + async workflows).

• Shoot for Impossible and Make it Happen
  :
  Sets audacious goals that others might see as unreachable and breaks them into actionable steps. Relentlessly perseveres through obstacles with resourcefulness and determination, turning ambitious vision into tangible results.
• Radical Candor…