6,000+ Customers. 300+ Integrations. Your Code Moves the Data.

At Windsor.ai, we connect data from 300+ sources (Facebook Ads, Google Ads, GA4, HubSpot, Salesforce, TikTok) to 30+ destinations (Looker Studio, BigQuery, Snowflake, and LLMs like ChatGPT and Claude). We're a lean, highly technical remote team serving 6,000+ customers, and we're looking for a Backend Engineer to help scale the platform behind it.

The Role

You'll build and maintain the Python pipelines at the core of our marketing data integration and ELT platform: pulling data from third-party APIs, normalizing it, and delivering it reliably at scale.

• Own API integrations end to end: rate limits, pagination, custom authentication, and inconsistent error handling across hundreds of sources.
• Ship production-grade code: clean, tested Python with pytest coverage and code review as routine.
• Keep pipelines fast and reliable: concurrency, caching, and smart data modeling as volume grows.
• Work async with a small, senior team: engineers, product, and support. Basic SQL is expected of everyone.

Stack: Python (Flask,



multi-threading), pytest / pytest-xdist, pylint, PostgreSQL, Redis, Linux, Docker, GitLab CI/CD, Taiga.

Who You Are

• 4+ years of professional programming experience with strong production-grade Python
• Solid grasp of OOP, concurrency (threads/async), and data structures
• Comfortable in Linux development and production environments
• Experience integrating third-party APIs and dealing with their quirks
• Independent, async, and comfortable in a fully remote, contractor-style engagement

Bonus: ETL/ELT or data integration experience

• marketing/ad-tech APIs
• PostgreSQL and Redis in production
• Docker and GitLab CI/CD

The Offer

• Competitive Pay / Contractor role
• Fully remote
• Real impact: your code runs in production for 6,000+ customers

Windsor.ai is a general team of data engineers and analysts who strive to make data integration effortless and insights easy to extract to eve

📌 Backend Engineer (Madrid)
🏢 Windsor.ai
📍 Madrid