Zehao J.

✅ 6+ Years of Full-Stack Engineering Experience ⚡ Production LLM / RAG / Agent Systems ⚡ AI-Powered Development for Faster Delivery & Better Code Quality 👀 Click Invite or Hire for AI features that ship in real products — not demos Looking for an engineer who can put LLMs into production — RAG, agents, and backend services that stay reliable after launch? For 6+ years I’ve built backend systems end to end: APIs, data models, auth, payments, and cloud deployment. Over the last stretch of that work I’ve focused on wiring Claude and OpenAI into real product flows: retrieval pipelines, multi-turn assistants, and agent-style workflows that call tools and write back to the backend. Primary stack: Java + Python, with PostgreSQL / Redis / Qdrant for data and retrieval. I care about systems that are clean to maintain, cheap enough to run, and ready to scale. What I can do for you: 𝐋𝐋𝐌 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐢𝐨𝐧 & 𝐏𝐫𝐨𝐦𝐩𝐭 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠 | Claude API · OpenAI · Prompt Design · Connect Claude or OpenAI into live product workflows (not notebook demos) · Design prompts and output contracts that your backend can parse and act on · Multi-turn dialogue with session state, context windows, and failure handling · Guardrails: retries, timeouts, rate limits, logging, and cost control 𝐑𝐀𝐆 𝐒𝐲𝐬𝐭𝐞𝐦𝐬 | Embeddings · Qdrant · Retrieval Pipelines · Spring Data · Design chunking, embedding, and indexing pipelines · Store and query vectors in Qdrant (similarity search, metadata filters) · Build retrieval → context assembly → generation loops behind REST APIs · Cache hot retrieval paths with Redis; tune for latency and answer quality 𝐀𝐈 𝐀𝐠𝐞𝐧𝐭𝐬 & 𝐀𝐮𝐭𝐨𝐦𝐚𝐭𝐢𝐨𝐧 | Tool Calling · Event-Driven Workflows · Backend Orchestration · Agent-style flows: model decides → backend tools run → results return to the model · Hook LLM steps into queues, webhooks, and scheduled jobs · Automations that touch your DB, payments, notifications, or third-party APIs · Keep agent logic testable and observable inside a normal Spring service layer 𝐁𝐚𝐜𝐤𝐞𝐧𝐝 𝐀𝐏𝐈 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐦𝐞𝐧𝐭 | Java · Spring Boot · Spring MVC · Spring Security · JWT · Design and build RESTful APIs from scratch · Implement authentication & authorization (JWT, Spring Security, role-based access control) · Structure business logic that is clean, testable, and maintainable 𝐃𝐚𝐭𝐚 & 𝐈𝐧𝐟𝐫𝐚𝐬𝐭𝐫𝐮𝐜𝐭𝐮𝐫𝐞 | PostgreSQL · MySQL · Redis · Docker · Nginx · CI/CD · Schema design, migrations, complex queries, performance work · Production setup on DigitalOcean: Docker, Nginx, SSL, CI/CD · Stripe subscriptions/webhooks when billing sits next to AI features 𝐅𝐫𝐨𝐧𝐭𝐞𝐧𝐝 𝐂𝐨𝐥𝐥𝐚𝐛𝐨𝐫𝐚𝐭𝐢𝐨𝐧 | Vue3 · Nuxt.js · TypeScript · Tailwind CSS · Work alongside frontend teams or handle supporting frontend work independently · Define API contracts, handle CORS, integrate backend services end-to-end I communicate clearly, deliver on schedule, and am comfortable working independently from requirements through to deployment. Feel free to reach out with your project.