Staff Software Engineer

Barcelona, Spain | Sept. 3, 2026

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Company: Supersonik

Country: Spain

Type: Hybrid remote

Employment: Full-time

Description: 🚀 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

Apply here:

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