Backend Architect for AI Pipelines (Node.js & MongoDB)

Wellfound; Barcelona; On-site; EUR 65,000 - 85,000; Full time

Job summary

Migma, a budding AI email platform based in Barcelona, is seeking a backend engineer to join the two-person founding team. You will ship Node.js services and APIs, optimize MongoDB data models, and drive AI generation workflows end-to-end.

Work directly with the founders on infrastructure, integrations, and AI pipelines, balancing speed with reliability, security, and cost efficiency. Barcelona-based, in-office collaboration is required.

Qualifications

• Strong experience running Node.js backends in production.
• Practical MongoDB knowledge, including query performance, indexing, and data architecture.
• Experience shipping LLM-powered features or AI pipelines, with an understanding of their failure modes.
• Ability to explain how you measure AI output quality, latency, reliability, and cost.
• Strong API design, debugging, security, and problem-solving skills.
• Ownership, clear communication, and comfort working in a small team.
• Already based in Barcelona and able to work with the founding team in person.

Responsibilities

• Build and maintain Node.js services and APIs.
• Improve MongoDB queries, indexes, and data models.
• Develop AI generation workflows and improve the quality and consistency of their outputs.
• Handle queues, retries, rate limits, provider failures, and cost metering.
• Add useful monitoring and tests around critical workflows.
• Build product integrations and improve backend performance and reliability.

Skills

Node.js

MongoDB

API design

Security

Distributed systems

AI pipelines

Tools

Express

BullMQ

Redis

Python tooling

Job description

Migma, a budding AI email platform based in Barcelona, is seeking a backend engineer to join the two-person founding team. You will ship Node.js services and APIs, optimize MongoDB data models, and drive AI generation workflows end-to-end.

Work directly with the founders on infrastructure, integrations, and AI pipelines, balancing speed with reliability, security, and cost efficiency. Barcelona-based, in-office collaboration is required.