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
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📌 Senior AI Software Engineer – Real-Time Voice (Barcelona)
🏢 Concentric Recruitment
📍 Barcelona