Senior Python Developer_AI

We’re looking for a Backend Engineer who has real production experience, knows how to build stable systems, and wants to dive into LLM agents not “because the task says so,” but because the topic genuinely excites them. We need someone with the vibe of “let’s build a smart assistant and ship a working product,” not “I’ll do my part until lunch.”

Must-have skills:

• 7+ years of software development experience;
• 5+ years of Python experience;
• API design approaches: REST / gRPC / GraphQL;
• Understanding of the HTTP protocol;
• How relational databases work: PostgreSQL or similar;
• How distributed/vector stores work: Weaviate, Cassandra, or similar;
• Python libraries/frameworks for building APIs: FastAPI, Flask, etc.;
• Asynchronous Python: asyncio, threads;
• Approaches to long-running background tasks/pipelines: Celery, Taskiq, Airflow, etc.;
• Containerization: Docker, Kubernetes, or Nomad;
• Message queues/brokers: Kafka, RabbitMQ, Redis, or similar;
• How to craft prompts for LLMs: system prompts, user queries, few-shot setups.

Nice to understand:

• How modern LLMs work: high-level understanding of neural networks, transformers, training, and serving;
• What the latest models are and how they differ;
• MCP (Model Context Protocol);
• General ML training/evaluation methodology: train/val/test, metrics;
• Core approaches and frameworks for building agents: fastmcp, mcp-use, OpenAI Agents SDK, or similar.

Nice-to-have:

• Experience building products with 10K+ MAU;
• Experience with “vibe coding” and tools like Cursor (or equivalents);
• Your own agent project (even a hobby one);
• Knowledge of other languages: Go, Rust, etc.

We offer:

• Flexible schedule - you choose when to start your day;
• Relocation to Bilbao, Spain for you and your family, with full support at every stage (documents, housing, adaptation, even pets);
• Unlimited vacation - take time off when you really need it;
• A culture of trust and respect for professionals, with no micromanagement;
• A modern office in a cozy district, regular team events and off-sites;
• Growth and participation in architectural decisions, challenging tasks, and a strong team you can learn from.