Staff Software Engineer

Supersonik is looking for a Staff Engineers (10+ years of experience)

Salary:
80-120k + significant equity

Onsite in Barcelona

Perks:
High ownership, fast learning cycles, tight-knit team, A16z-backed company, real impact from day one

Summary:

Supersonik is redefining how B2B SaaS companies sell. Their AI Agent delivers personalized, real-time product demos
on live calls
, helping teams skip long sales cycles and close deals faster. Backed by
Andreessen Horowitz (a16z)
, they're scaling globally and building a technical foundation where performance, AI, and great UX come together. They're now hiring
Staff Engineers
to join the core team in Barcelona. If you thrive in high-growth environments, love solving complex engineering challenges, and want to build lightning-fast, event-driven systems using modern Python, this role has your name on it.

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 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
• Full ownership, real impact, and fast learning cycles
• A tight-knit team that values clarity, speed, and smart execution

About JobFluent

ES - ¿QUÉ SOMOS?

JobFluent es un híbrido entre una plataforma de empleo tecnológico de calidad y un equipo de asesores que te ayudan a crecer en tu carrera. Nuestro objetivo es que la vida de nuestros usuarios cambie a mejor y que el proceso de cambio (normalmente estresante) sea lo más FLUIDO y agradable posible .

Somos conocidos por:

Trato humano: nuestro equipo siempre está preparado para ayudarte de forma honesta y personalizada.

Sin spam: primero te escuchamos y sólo después te sugerimos oportunidades relevantes y validadas que encajen con tus intereses e inquietudes.

Acompañamiento: te damos consejos y te apoyamos durante todo el proceso de selección para aumentar tus probabilidades de éxito.

Experiencia del candidato: esto es lo que nos mueve Nos rebelamos contra la falta de feedback y otras malas prácticas demasiado habituales en nuestro mundo.

EN - WHO WE ARE

JobFluent is a hybrid between a quality tech job platform and a team of advisors who help you grow your career. Our goal is to make our users' lives change for the better and to make the (usually stressful) job search process as FLUENT and enjoyable as possible .

We are known for:

Human treatment: our team is always ready to help you in an honest and personalized way.

No spam: first we listen to you and only then do we suggest relevant and validated opportunities that match your interests and concerns.

Coaching: we give you advice and support you throughout the selection process to increase your chances of success.

Candidate experience: this is what drives us We rebel against the lack of feedback and other bad practices that are all too common in our world.