Senior Backend Engineer — AI Voice Agent Platform (All Levels)

Vantaca; Redwood City (CA); On-site; USD 120,000 - 160,000; Full time

Benefits offered by this job

Unlimited PTO

401K with Company Match

Medical, Dental, and Vision coverage

Job summary

Vantaca is looking for a Backend Engineer to join our HOAi team in Redwood City, CA. You will own backend services for a production-grade AI voice agent platform, ensuring real-time performance and reliability. Ideal candidates have over 6 years of experience in backend engineering and a strong grasp of distributed systems. We offer competitive benefits like unlimited PTO, medical coverage from day one, and a flexible remote work policy. Join us to transform community management with cutting-edge AI technology.

Qualifications

• 6+ years of backend engineering experience owning production systems.
• Strong understanding of distributed systems with operational best practices.
• Experience in building and operating low-latency systems.

Responsibilities

• Own voice agent backend services for session lifecycle and call routing.
• Build streaming pipelines for STT/TTS integration and latency management.
• Implement tool calling and manage agent runtime.

Skills

Backend engineering experience

Distributed systems fundamentals

Data modeling and API design

Real-time systems experience

Tools

WebRTC

Twilio

Job description

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.

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.

What You’ll Do

• 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.

What We’re Looking For

• 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 Have

• 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).

HOAi Way

• 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 Leads to Humble Excellence: Gives and receives direct, honest feedback with genuine care for others' growth. Stays open‑minded on the path to continuous improvement, recognizing that the best outcomes come from carrying no ego.
• Hire and Develop the Best Talent: Actively seeks exceptional people who raise the bar and invests deeply in their growth. Creates opportunities for team members to stretch their capabilities, providing coaching and support that helps them reach their full potential.

Why You Should Join Our Team

• 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.