Backend Engineer (Node.js/NestJS) —Lisbon, Portugal em Lisboa, Portugal

### **About Us** We are a **stealth-mode startup** building a new AI platform. Our mission is to make advanced language models deployable, customizable, and secure across diverse environments. ### **Role** We are seeking a **Backend Engineer (https://jobeax.com/link/k0MXLUXcpjpZfTVN to extend our platform using our existing codebase. You'll build the **proxy backend** that interacts with our custom inference runtime and extend dashboards. This role requires strong backend engineering skills, the ability to integrate existing systems, and comfort working closely with C++/CUDA engineers building low-level runtime features.

• ## **Responsibilities**
• ### **Proxy Backend for Inference Runtime**

• Build and maintain a **Node.js-based proxy backend**that:
• Accepts inference requests from the frontend.
• Schedules and serializes prompts.
• Manages **QKV cache load/unload**.
• Provides APIs to **manage LoRA adapters**.
• Integrate with authentication, RBAC, and logging already provided by the existing stack.
• Expose metrics and logs for monitoring inference usage and performance.

#### **Dashboards**

• Extend the existing Dashboard with Dataset upload, training job view, model management, inference usage, request history, and adapter selection.
• Reuse **auth, billing, and user management code** (Auth0, Stripe).
• Add necessary backend endpoints to support new UI flows.

#### **Core Stack & Infrastructure**

• Develop using **NestJS** as the main backend framework.
• Work with **PostgreSQL, Redis, and HashiCorp Vault** for persistence, caching, and secrets.
• Use **Socket.IO** for real-time updates (job status, inference progress).
• Ensure secure integration with Stripe (billing) and Auth0 (identity).
• Collaborate with DevOps on deployment pipelines (Proxmox, Docker, CI/CD).

### **Requirements**

• Strong experience with **Node.js** and **NestJS** framework.
• Proficiency in **PostgreSQL** and **Redis** for persistence and caching.
• Hands-on experience with **Socket.IO** or other WebSocket libraries.
• Experience with **secure configuration and secrets management** (HashiCorp Vault preferred).
• Comfortable working with **microservices** and integrating with existing codebases.
• Strong debugging and systems thinking — able to reason about scheduling, state management, and concurrency.
• Familiarity with LangChain for building AI-powered features and workflows.

### **Nice to Have**

• Experience integrating with **AI runtimes** (gRPC/REST backends for inference).
• Experience with RAG and MCP.
• Experience with **authentication/authorization frameworks** (Auth0, JWT, RBAC).
• Familiarity with **Stripe API** or similar billing systems.
• Contributions to backend open-source projects.
• Experience with WebRTC.

### **Why Join**

• Extend a proven SaaS foundation into a **new AI runtime platform**.
• Competitive compensation, equity potential.