Senior Backend Engineer — AI Agents Platform (All Levels)
AI summary of the role
Senior Backend Engineer role owning the backend systems for a vertical AI agent platform at HOAi, a fast-growing startup acquired by Vantaca.
What you’ll do
- Own core backend services powering agents: build and operate 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 supporting agent memory/state, workflow history, audit trails, permissions, and multi-tenant isolation.
- Implement and maintain high-quality integrations (OAuth, webhooks, sync engines, connectors) with strong observability and failure handling.
What you’ll bring
- 6+ years building backend systems for production SaaS, platforms, or distributed systems.
- Strong fundamentals in distributed systems, concurrency, queues/workers, caching, and production operations.
- Excellent relational modeling (Postgres/MySQL), migrations, indexing, query optimization, and data correctness.
- Proven ability to design clear, evolvable APIs and contracts across services and external partners.
Technologies
Postgres · MySQL · OAuth · webhooks · LLM · Vercel AI SDK · LangChain · LangGraph · Anthropic Agents SDK · OpenAI tool calling
Source and classification
Internal deployment & tooling · Evidence for this classification:
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
More from the 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 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 le [... source excerpt omitted ...] ute 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, we [... source excerpt omitted ...] 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 withou
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