Software Development Engineer (Front End)

Software Engineer About the Role We re hiring Software Engineers (5+ years of experience) to join our core team in Barcelona. You ll be solving complex, technical problems and shaping the product and architecture from day one. You should thrive in high-growth startup environments, be fluent in modern Python and async programming and know how to build scalable, event-driven systems.

You care about fast, real-time systems and enjoy working at the intersection of performance, AI and great user experience. If you love solving first-principles problems, navigating ambiguity and want to build a product people love you ll fit right in. What You ll Work On Scale a real-time, event-driven backend architecture where milliseconds matter

Design and implement low-latency APIs using FastAPI and Asyncio

Solve engineering challenges in performance optimization, observability, and resilience

End to end contributions from frontend to infrastructure.

Collaborate on prompt engineering, LLM behaviors, LLM fine-tuning and UX

Build and maintain infrastructure-as-code with Terraform and AWS

Contribute to 0 1 product development with a small, fast-moving team Our Stack Backend: Python, FastAPI, Asyncio, Redis, PostgreSQL

Infra: AWS, Terraform, CI/CD

Frontend: React

Tooling: GitHub, Datadog, Linear Bonus Points Experience with LLMs (prompting, training, alignment)

Experience with TTS, STT and real-time voice

Experience with browser automations

Deep knowledge of AWS, Terraform, and distributed systems

Experience shipping 0 1 products in a startup What You ll Get Above-average salary

Significant equity in a company backed by A16z Async, AWS, Python,