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 Software Engineer C# (Cataluña)
🏢 Concentric Recruitment
📍 Cataluña