Senior Backend Engineer — AI Agents Platform

Vantaca, LLC; Redwood City (CA); Hybrid; USD 150,000 - 210,000; Full time

Benefits offered by this job

Medical, Dental, and Vision benefits

Unlimited PTO

401K with Company Match

Flexible Remote Work

Parental Leave

Job summary

A leading technology startup is seeking a Backend Engineer to build and maintain reliable backend services for AI agents. The role requires expertise in distributed systems, API design, and data modeling. You will work in a high‑velocity environment where you will own critical aspects of the platform, enhancing performance and reliability. With a strong growth trajectory and innovative AI solutions, this position offers a dynamic work environment and the chance to work on cutting-edge technology.

Qualifications

• 6+ years building backend systems for production SaaS, platforms, or distributed systems.
• Strong fundamentals in distributed systems, concurrency, queues/workers, and caching.
• Proven ability to design clear, evolvable APIs and contracts.
• Ability to design clear, evolvable APIs and contracts across services and external partners.
• Ability to work in fast-paced environments while maintaining reliability and security.
• Ownership mentality: build → ship → operate with minimal supervision.

Responsibilities

• Own core backend services powering agents.
• Design robust APIs and contracts.
• Model complex domain data and design schemas.
• Implement and maintain high-quality integrations (OAuth, webhooks, connectors) with observability and failure handling.
• Define and improve SLIs/SLOs, tracing, safety rails, and incident response.
• Optimize throughput, latency, queues, caching, storage, and tool-call costs; guard runaway tasks.
• Raise engineering standards: code quality, testing, on-call hygiene, runbooks, postmortems, mentoring.

Skills

Distributed systems

Concurrency

API design

Data modeling

Backend systems

Production operations

Job description

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 rebuilding 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.

What you’ll do

• 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.

What we’re looking for

• 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 have

• 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.

The 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.

We receive many resumes for our open positions and each one is reviewed by a human being on our recruiting team. We will compare your background with the qualifications and requirements for the position. If you are selected for an interview you will receive an e‑mail from someone on our recruiting team with an @vantaca.com email address. It may take some time for us to review all of the applications so give us some time to respond. We appreciate your interest in this role.