Senior Software Engineer
Summary
Senior/Principal Software Engineer (hired via Concentric Recruitment for its client) building the platform behind AI voice agents at a Barcelona startup: owning features end-to-end across a TypeScript/Python/React stack, working on LLM orchestration, STT/TTS pipelines and real-time systems. Hybrid in Barcelona, fluent Spanish required, €80k–€100k + equity.
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
If this role sounds interesting, and you think you have the required experience, please contact me directly.
Email: cristian@weareconcentric.com | Follow me
Concentric Recruitment is a boutique recruitment firm focused primarly on recruitment for Cloud, DevOps and AI Engineering roles.
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