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

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📌 Senior Software Engineer (Madrid)
🏢 Concentric Recruitment
📍 Madrid