Staff Software Engineer

🚀 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.

🧩 About the Role

We’re hiring Staff Engineers (10+ 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 (or willing to learn) 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

Hybrid model with preference for onsite work

Full ownership, real impact, and fast learning cycles

A tight-knit team that values clarity, speed, and smart execution