Senior Software Engineer

Concentric Recruitment; Madrid; Híbrido; EUR 80.000 - 100.000; Jornada completa

Ventajas ofrecidas por este puesto de trabajo

Equity

Descripción de la vacante

Concentric Recruitment is seeking a Senior/Principal Software Engineer to join a Barcelona-based hybrid team building AI-driven communication products. The role requires 5+ years in production with modern web tech and fluency in Spanish.

You will develop scalable APIs, real-time voice services, and integrate LLM/AI stacks. Collaboration with founders and senior engineers will shape the platform's architecture and strategy.

Formación

• 5+ years of production experience with a modern web stack.
• Experience with TS/JS/Python or C#.
• Experience with AI coding agents such as Claude Code, Cursor or Codex.
• Fluent Spanish; comfortable working in a hybrid Barcelona setting.

Responsabilidades

• Build scalable APIs and services for real-time voice interactions.
• Develop product features end-to-end with React, TypeScript and AI infrastructure.
• Integrate LLM, STT and TTS workflows into production.
• Work on agentic and multi-agent workflows.
• Improve architecture, observability, testing and engineering quality.
• Collaborate directly with founders and senior team to shape the platform.

Conocimientos

5+ years production experience

TypeScript/JavaScript/Python/C#

AI agents experience

Docker

SQL

Testing

Scalable architecture

Fluent Spanish

Herramientas

LangChain

LangGraph

AWS

GCP

CI/CD

Descripción del empleo

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.

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