Senior Software Engineer

Concentric Recruitment; España; Remote; EUR 90,000 - 120,000; Full time

Job summary

Concentric Recruitment is partnering with a client building AI-driven communication products. They seek a Senior/Principal Software Engineer to own features end-to-end on a TypeScript/Python stack and contribute to AI pipelines, LLM orchestration, and real-time systems for voice agents.

You will build scalable APIs and services for real-time interactions, collaborate with founders and senior engineers, and help shape the platform's architecture, reliability, and performance in a fully remote

Qualifications

• 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.

Responsibilities

• 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.

Skills

7+ years production experience

AI coding agents

Product mindset

Docker

SQL

Testing

Scalable architecture

Spanish language

Tools

LangChain

LangGraph

AWS

GCP

CI/CD

Observability

Job description

Role: Senior / Principal Software Engineer

Job Type: Full-Time

Contract Type: Direct employment with our client

Location: Remote in Spain

Language: Fluent Spanish is required

Visa sponsorship is not available for this role

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

• +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

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