Senior Backend Engineer

## About the role HelioAI (helioai.tech) is building a reliable AI concierge for Shopify brands, helping shoppers get accurate answers, discover products faster, and complete purchases with confidence, while reducing support workload for brands. We're looking for a senior backend engineer to own our backend architecture end to end. You'll design the systems that power AI conversations across hundreds of Shopify storefronts, build the agent infrastructure that runs catalog, order, and policy tools at scale, and set the engineering bar for the rest of the team. You'll work directly with the founders on architecture decisions and roadmap. Real production systems, real load, real customers (Soulflower, Nysh, Ashpveda, SarinSkin, Bake, and growing). ## What you'll do - Own backend architecture for Node.js + TypeScript services across AI, Shopify, and platform layers - Design and scale the agent runtime: tool registry, brand config scoping, conversation state, structured RAG, prompt caching - Build reliable Shopify infrastructure: Admin API integrations, webhook pipelines, store sync, rate limit handling, idempotency - Lead data architecture decisions across MongoDB, Postgres, Redis, and queues; own scaling, indexing, and cost - Drive observability and reliability: logging, tracing, alerting, SLOs, incident response - Build conversation to order attribution, billing, and usage metering across monthly and variable plans - Set the bar on code quality, PR review, testing, and deploy hygiene - Mentor backend interns and engineers, run design reviews, write the docs that scale the team ## What you'll work on (examples) - Agent runtime powering live conversations across hundreds of Shopify storefronts - Shopify onboarding, store sync, and high throughput webhook pipelines - Tool layer for catalog fetch, order status, policies, FAQs, recommendations, escalations - Billing and usage tracking across monthly and variable plans - Conversation to order attribution infrastructure - MongoDB Atlas scaling, Redis caching strategy, BullMQ job pipelines ## What we expect - 5+ years building production backend systems, ideally 3+ on Node.js + TypeScript - Shipped and operated systems at meaningful scale, not just CRUD behind an LLM call - Strong on at least one of MongoDB or Postgres at a level beyond "I write queries", schema design, indexes, query plans, scaling tradeoffs - Real experience with Redis, queues (BullMQ or similar), and async workflows with retries, idempotency, and backpressure - Comfortable owning incidents, observability, and cost - Care about API design, contracts, and clean boundaries between services - Async, written communication first, low ego, ships small and often ## Nice to have - Built Shopify apps or worked deeply with Shopify Admin APIs and webhooks at scale - Production experience with LLM systems: agent loops, tool calling, RAG, prompt caching, eval pipelines - GraphQL at scale (server side, not just consuming) - Multi tenant SaaS architecture (brand config scoping, isolation, per tenant rate limits) - Open sour