Role: Senior / Principal Software EngineerJob Type: Full-TimeSalary range: to €100.000 + EquityContract type: Direct employment with our clientLocation: Onsite in BarcelonaOnly interested in speaking with candidates who are comfortable working from the office 5 days per weekOur 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 stackExperience with AI coding agents such as Claude Code, Cursor or CodexReal Product mindset and ability to work autonomouslyComfortable with Docker, SQL,



testing and scalable architectureFluent Spanish and EnglishNice to haveExperience with LLMs, STT/TTS, OpenAI, Whisper, ElevenLabs or DeepgramExperience with LangChain, LangGraph or similar AI orchestration toolsAWS/GCP, CI/CD and observability experienceStartup or early-stage product company experiencePRevious experince leading a team or acting as a principalWhat you’ll be doingBuilding scalable APIs and services for real-time voice interactionsDeveloping product features end-to-end with React, TypeScript and AI infrastructureIntegrating LLM, STT and TTS workflows into productionWorking on agentic and multi-agent workflowsImproving architecture, observability, testing and engineering qualityWorking directly with the founders and senior team to shape the platform
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📌 Senior Software Engineer (Barcelona)
🏢 Concentric Recruitment
📍 Barcelona