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# Senior Backend Developer

- **Company:** Kolsquare
- **Location:** Paris, France (Remote available)
- **Experience:** Expert
- **Contract:** Permanent contract
- **Skills:** Clean Code Principles, Application Programming Interfaces (APIs), Software as a Service, Software Quality, Code Review, Continuous Integration, Relational Databases, Database Queries, DevOps, Distributed Systems, Elasticsearch, MySQL, Performance Tuning, Query Optimization, Ruby on Rails, Systems Architecture, Backend, Front End Software Development, Restful APIs
- **Published:** June 3, 2026
- **Apply:** https://fr.indeed.com/viewjob?jk=48f1c62f5ab3ea8e

## About the Role

* Strong experience with Ruby on Rails in production environments
 * Solid experience designing and maintaining RESTful APIs
 * Hands-on experience with Elasticsearch or search systems
 * Strong knowledge of relational databases (MySQL preferred) and query optimization, * Experience working on SaaS platforms or high-scale applications
 * Familiarity with cloud environments (GCP) and CI/CD pipelines
 * Experience with performance optimization, background jobs, and distributed systems

## Description

* Be Responsible in your actions
 * Pursue Growth & Learning
 * Be passionate and determined
 * Share your Power, Knowledge & Wealth
 * Build Authentic relationships

We cultivate a culture of inclusion for all employees that respects their individual strengths, views, and experiences. We believe that our differences enable us to be a better team - one that makes better decisions, drives innovation, and delivers better business results., We are looking for an experienced Senior Backend Developer to join our team and help build, scale, and maintain our SaaS platform. You will play a key role in designing robust backend systems, improving performance, and delivering high-quality features that power our product.

Backend Development & Feature Delivery (50%) : Design, develop, and maintain backend services and APIs using Ruby on Rails. Implement new features for the SaaS platform, write clean and maintainable code, and ensure the scalability and performance of the application.

System Architecture & Performance Optimization (30%) : Contribute to backend architecture decisions, improve system scalability, and optimize database queries and search performance using Elasticsearch. Ensure the platform remains reliable and performant as the product grows.

Collaboration, Code Quality & Technical Leadership (20%) : Collaborate with product, frontend, and DevOps teams to deliver high-quality features. Participate in code reviews, maintain testing standards, contribute to CI/CD processes, and support best engineering practices within the team.


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