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 Read full job description Read full job description LinkedIn login required * I agree to JobFluent's Terms of Use and Privacy Policy About Supersonik Website https://supersonik.ai/ Industry Ai Headquarters Barcelona, Spain Company Size 2-10 Founded 2024 Supersonik is reshaping how B2B SaaS companies sell their software. Our AI Agents deliver instant, personalized, interactive, and multi-language product demos at scale, combining the discovery, qualification, and demonstration steps for a faster sales cycle and increased revenue. We’re replacing outdated sales cycles with smart, dynamic AI-driven experiences, and we’re just getting started. Other backend developer jobs that might interest you... Software Engineer - Backend at Cala added yesterday Backend Developer AI SQL Python NoSQL Kubernetes FastAPI Amazon Web Services (AWS) Backend Developer AI SQL Python NoSQL Kubernetes FastAPI Amazon Web Services (AWS) Staff Backend Engineer at Preply added yesterday Backend Developer Edtech APIs Backend Developer Edtech APIs Java Architect at eDreams ODIGEO added yesterday Backend Developer Travel Java Backend Developer Travel Java 2026 © JobFluent. Crafted in Barcelona. Careers Companies For employers Sitemap Blog About Terms of Use Legal Notice Privacy Policy & Cookies English Spanish Valencia Barcelona Madrid Remote Jobs Companies For employers Recruit Talent Post a job English Spanish Blog About We use our own cookies and cookies from third parties to measure your activity in this website and improve the service through analysis of your browsing activity. If you continue browsing, we consider that you accept their use. You can change this configuration and obtain more information here . I understand $(function() { jobsBCN.OfferPills.init(); jobsBCN.OfferDetails.init('bef737', '/offers/staff-software-engineer-barcelona--bef737/external_applied', '0', true, "You need to agree to JobFluent's Legal Terms and Privacy Policy before proceeding."); jobsBCN.OfferPage.init('bef737', 0); jobsBCN.Search.start({ url: '/jobs-barcelona', logPath: '/log_search' }); $.getScript('/offer_subscriptions/new?location_id=barcelona&offer_id=bef737'); jobsBCN.Company.track('Employer-branding-job-page-CTA'); }); jobsBCN.SearchAutocomplete.start({ url: '/autocomplete' }); $(function() { jobsBCN.sideMenu(); }); $(function() { jobsBCN.scrollTop(); retinajs(); });