Senior Real-Time Backend Engineer (Python, AI)

Supersonik; Barcelona; On-site; EUR 70,000 - 110,000; Full time

Benefits offered by this job

Equity

Ownership

Fast learning

Job summary

Supersonik seeks Senior Engineers to join our core team in Barcelona. You will tackle complex technical problems, shape product architecture from day one, and thrive in a fast-growing startup. You should be fluent in modern Python, async programming, and adept at building scalable, event-driven systems.

You’ll work across frontend to infrastructure to deliver high-performance demos. If you love first-principles thinking, ambiguity, and delivering products people love, you’ll fit right in with

Qualifications

• Strong experience in backend engineering with Python (FastAPI) and async programming.
• Experience building real-time, low-latency systems.
• Ability to work across frontend to infrastructure.
• Startup environment experience and fast learning mindset.

Responsibilities

• 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, observability and resilience.
• End-to-end contributions from frontend to infrastructure.
• Collaborate on prompt engineering, LLM behaviors, and UX.
• Build and maintain infrastructure-as-code with Terraform and AWS.
• Contribute to 0→1 product development with a small, fast-moving team.

Skills

Python

Async programming

Real-time systems

Distributed systems

Problem solving

Tools

FastAPI

Asyncio

Redis

PostgreSQL

Terraform

AWS

React

GitHub

Datadog

CI/CD

Job description

Supersonik seeks Senior Engineers to join our core team in Barcelona. You will tackle complex technical problems, shape product architecture from day one, and thrive in a fast-growing startup. You should be fluent in modern Python, async programming, and adept at building scalable, event-driven systems.

You’ll work across frontend to infrastructure to deliver high-performance demos. If you love first-principles thinking, ambiguity, and delivering products people love, you’ll fit right in with