Role: Senior / Principal Software Engineer Job Type: Full-Time Salary range: to €100.000 + Equity Contract type: Direct employment with our client Location: Onsite in Barcelona Only interested in speaking with candidates who are comfortable working from the office 5 days per week 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 ~+5-7 years of production experience with modern web stack ~ 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 and English 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# - (Hybrid Remote) (Barcelona)
🏢 Concentric Recruitment
📍 Barcelona