Senior Backend Engineer — AI Agents Platform

Vantaca+HOAi•Redwood City, CA

6h•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 large-scale, highly reliable platform for vertical AI agents. Our agents execute real workflows: they call tools, integrate with third-party systems, and operate over complex, evolving data. This role owns the backend systems that make agents dependable in production—agent runtime services, integrations, data modeling, observability, and platform reliability. You will work in a high-velocity environment with real ownership: you’ll design systems, ship quickly, measure outcomes, and harden the platform as it scales.

Requirements

Experience: 6+ years building backend systems for production SaaS, platforms, or distributed systems.
Backend depth: strong fundamentals in distributed systems, concurrency, queues/workers, caching, and production operations.
Data modeling strength: excellent relational modeling (Postgres/MySQL), migrations, indexing, query optimization, and data correctness.
API design excellence: proven ability to design clear, evolvable APIs and contracts across services and external partners.
High pace + high quality: you thrive in fast-moving environments without sacrificing reliability or security.
Curiosity and ownership: you enjoy ambiguous problems, learn quickly, and take systems end-to-end (build → ship → operate).

Nice To Haves

LLM experience: building product with LLMs (prompting, tool calling, evals, latency/cost tradeoffs).
Agent architecture familiarity: orchestration patterns, planning/execution loops, memory/state, sandboxed tool execution, human-in-the-loop, safety constraints.
Framework familiarity: Vercel AI SDK, LangChain/LangGraph, Anthropic Agents SDK, OpenAI tool calling, sandboxing/tool runtimes.

Responsibilities

Own core backend services powering agents: build and operate the agent runtime services (tool execution, state management, orchestration, retries, idempotency, rate limiting).
Design robust APIs and contracts: develop stable, well-versioned APIs (internal + external), including webhook/event interfaces and integration adapters.
Model complex domain data: design schemas and data access patterns that support agent memory/state, workflow history, audit trails, permissions, and multi-tenant isolation.
Integrations at scale: implement and maintain high-quality integrations (OAuth, webhooks, sync engines, connectors) with strong observability and failure handling.
Reliability engineering: define and improve SLIs/SLOs, implement end-to-end tracing, build safety rails (timeouts, circuit breakers, budgets), and run incident response.
Platform performance and cost control: optimize throughput/latency, queue backlogs, caching, storage, and inference/tool-call costs; build guardrails for runaway tasks.
Raise engineering standards: drive code quality, testing strategy, on-call hygiene, runbooks, postmortems, and mentoring.

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.