Role: Senior / Principal Software Engineer Sector: Artificial Intelligence Job Type: Full-Time Salary: €80,000–€100,000 + Equity Contract Type: Direct employment with our client Location: Hybrid – Barcelona Language: Fluent Spanish is required Visa sponsorship is not available for this role (Only interested in speaking with candidates who are comfortable working in a hybrid model) Our partner is building next-generation AI-driven communication products that help businesses automate customer interactions, improve operational efficiency and generate actionable insights in real time.

What we are looking for ~+5 years of production experience with modern web stack ~ Production experience with TypeScript, JavaScript, Python or C# ~ Experience with AI coding agents such as Claude Code, Cursor or Codex ~ Real Product mindset and ability to work autonomously ~ Comfortable with Docker, SQL,



testing and scalable architecture ~ Fluent Spanish Nice to have Experience with LLMs, STT/TTS, OpenAI, Whisper, ElevenLabs or Deepgram Experience with LangChain, LangGraph or similar AI orchestration tools AWS/GCP, CI/CD and observability experience Startup or early-stage product company experience Previous experince leading a team or acting as a principal What you’ll be doing Building scalable APIs and services for real-time voice interactions Developing product features end-to-end with React, TypeScript and AI infrastructure Integrating LLM, STT and TTS workflows into production Working on agentic and multi-agent workflows Improving architecture, observability, testing and engineering quality Working directly with the founders and senior team to shape the platform

📌 Senior Software Engineer C# - FLEXIBLE WORKING (Madrid)
🏢 Concentric Recruitment
📍 Madrid