Backend Engineer (Node.Js/Nestjs) —Lisbon, Portugal

Baasi; Lisboa; On-site; EUR 45,000 - 70,000; Full time

Benefits offered by this job

Competitive compensation

Equity potential

Job summary

A stealth-mode startup in Lisbon is seeking a Backend Engineer (Node.js/NestJS) to extend their AI platform. The role involves building and maintaining a Node.js-based proxy backend, integrating existing systems, and collaborating with a team focused on developing new AI runtime features. Strong experience with Node.js, NestJS, PostgreSQL, and Redis is essential. The position offers competitive compensation and the opportunity to work on pioneering technology.

Qualifications

• Strong experience with Node.js and NestJS framework.
• Proficiency in PostgreSQL and Redis for persistence and caching.
• Experience with secure configuration and secrets management.

Responsibilities

• Build and maintain a Node.js-based proxy backend.
• Integrate with authentication and logging provided by the existing stack.
• Expose metrics and logs for monitoring inference usage and performance.

Skills

Node.js

NestJS

PostgreSQL

Redis

Socket.IO

Microservices

Debugging

Tools

HashiCorp Vault

Docker

Proxmox

Job description

About the job Backend Engineer (Node.js/NestJS) —Lisbon, 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 (Node.js/NestJS) 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.
• 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.

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.