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 & LLM Platforms (Barcelona)
🏢 Concentric Recruitment
📍 Barcelona