About Supersonik Supersonik helps B2B SaaS companies sell faster with AI-powered product demos. On a live video call, our AI Agent shares the screen to walk buyers through a personalized, interactive demo in any language. This lets teams skip long sales calls and focus on closing deals.
We're backed by Andreessen Horowitz (a16z) and work with leading SaaS companies worldwide.
We're hiring Senior Engineers to join our core team in Barcelona.
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.
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
Backend: Python, FastAPI, Asyncio, Redis, PostgreSQL
Infra: AWS, Terraform, CI/CD
Frontend: React
GitHub, Datadog, Linear
Experience with LLMs (prompting, training, alignment)
Deep knowledge of AWS, Terraform, and distributed systems

📌 Vacancy: Software Engineer (Barcelona)
🏢 Supersonik
📍 Barcelona