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. They are now looking for a Senior/ Principal Software Engineer to help scale the platform behind their voice agents, owning features end-to-end across their TypeScript / Python stack and working on AI pipelines, LLM orchestration, STT/TTS, prompt workflows and real-time systems. 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 What You Need To Do Next

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