Senior Backend Developer - Architect & Streaming Expert Freelance 3-Month Mission H/F Posse

Posse is a Paris-based app studio building innovative mobile products with a strong focus on user experience, growth, and scalability. Our team designs and operates consumer apps used by hundreds of thousands of people worldwide.

We thrive on creativity, collaboration, and technical excellence, and we're now looking for a Senior Backend Developer (Freelance) to help us architect and scale the backend of our next-generation applications.

Role Overview

We're seeking a freelance Senior Backend Developer for a 3-month mission, focused on designing and implementing a robust, scalable backend architecture.

You'll take ownership of backend design choices, DevOps strategy, and scalability challenges including complex topics like video streaming performance and low-latency delivery.

This mission is both strategic and hands-on: you'll work closely with our product, front-end, and mobile teams to ensure reliability, speed, and future-proof scalability.

Key Responsibilities

- Design and deploy the complete backend architecture (APIs, authentication, security, documentation).
- Define technical choices across the stack (Node.js, Go, Python, SQL/NoSQL databases).
- Build and maintain DevOps infrastructure: CI/CD pipelines, monitoring, and cloud setup (AWS, GCP, or Azure).
- Collaborate with mobile and product teams to ensure seamless integration and performance.
- Tackle video streaming challenges: optimization, latency reduction, encoding, and delivery.
- Guarantee high-quality code standards, reliability, and security.
- Stay up-to-date with the latest backend and streaming technologies.

Profile

- 5+ years of experience in backend development and architecture.
- Expertise in at least one major backend stack (Node.js, Go, Python...).
- Solid DevOps experience and mastery of cloud environments (AWS, GCP, Azure).
- Strong understanding of distributed systems and microservices.
- Background or interest in video streaming / real-time processing is a plus.
- Autonomous, proactive, and comfortable working with lean startup teams.

Mission Details

- Contract type: Freelance
- Duration: 3 months
- Location: Paris or remote (CET time zone preferred)
- Start date: ASAP

Why Join Posse?

At Posse, you'll work on meaningful products with real-world impact, in a fast-moving and creative environment. We value autonomy, technical depth, and innovation. If you're a builder at heart who enjoys tackling architecture and performance challenges, we'd love to work with you.