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 Senior Engineers 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 matterDesign and implement low-latency APIs using FastAPI and AsyncioSolve engineering challenges in performance optimization, observability, and resilienceEnd to end contributions from frontend to infrastructure.Collaborate on prompt engineering, LLM behaviors, LLM fine-tuning and UXBuild and maintain infrastructure-as-code with Terraform and AWSContribute to 0→1 product development with a small, fast-moving teamOur Stack Backend: Python, FastAPI, Asyncio, Redis, PostgreSQLInfra: AWS, Terraform, CI/CDFrontend: ReactTooling: GitHub, Datadog, LinearBonus Points Experience with LLMs (prompting, training, alignment)Experience with TTS, STT and real-time voiceExperience with browser automationsDeep knowledge of AWS, Terraform, and distributed systemsExperience shipping 0→1 products in a startupWhat You’ll Get Significant equity in a company backed by A16zFull ownership, real impact, and fast learning cyclesA tight-knit team that values clarity, speed, and smart execution#J-18808-Ljbffr

📌 Software Engineer (Barcelona)
🏢 Supersonik
📍 Barcelona