Software Engineer – Freelance – Madrid

Software Engineer – Freelance – Madrid Overview

Requirements

What we're looking for

Mastery of React is an essential requirement.

We are looking for curious people ready to take on new challenges. We value a good understanding of technical challenges and a strong ability to adapt.

Beyond development, the role involves advising clients on the business value a digital project can bring. We therefore expect good written and verbal communication skills.

• You love modern, fluid, and pixel-perfect interfaces.

• You are not afraid to dive into complex business rules to turn them into efficient and optimized algorithms.

• You are fluent in using AI code editors like Cursor or Claude Code to increase your agility and execution speed, while always maintaining full control of your codebase.

• You have a way with people and enjoy accompanying sales teams to meetings to explain technical concepts clearly.

• You enjoy teamwork, but you have full autonomy in your tasks.

• You seek technical excellence in everything you do, with a solid engineering foundation.

Nice to have

• You have native-level Spanish and fluent English. Bonus points if you speak French!

Pay & benefits

What you'll get

• Salary: €210 /day

The role

This is not a one-off assignment: the goal is for you to join our pool of freelancers so we can regularly offer you assignments tailored to your profile. Assignments last 4 months on average, mostly full-time (5 days/week).

You will work autonomously, as part of a team (engineers, project managers, designers), in direct contact with the client and with a high level of responsibility.

We have had the opportunity to work on several occasions with the CEA (French Alternative Energies and Atomic Energy Commission), one of France’s leading scientific research organizations. Our latest project involved improving an open-source data annotation tool, whose outputs are used to train AI models. The project addressed multimodal data visualization challenges (2D, 3D, time series). Technically, the work covered redesigning the UI architecture, integrating NLP models and 3D point clouds, a backend data preprocessing pipeline, as well as an agentic dimension to automate the annotation process.

The FFTir (French Shooting Federation) called on us to modernize and replace its internal management tool: THOT, a platform that centralizes the management of its organizational structure (federations, regions, leagues, departments, associations) as well as its sports repositories. Given that the application manages a significant volume of personal data (members, contact details, sports histories), security and compliance challenges were at the heart of the project. On the technical side, the project relies on a fullstack TypeScript monorepo architecture with a granular permission system by feature and by entity, strict GDPR compliance, 2FA authentication, role-based access control, and traceability of sensitive actions; all designed to handle up to 200,000 simultaneous users during major events.

Project X Paris is a French fashion brand. Since 2018, we have been supporting PXP in the development and evolution of a complete application ecosystem, structured around its business challenges. From online checkout to internal tools, including B2B flows and logistics, we have supported the product’s growth by making lasting technical and architectural decisions. The project has been built on structuring choices to manage its increasing complexity: centralization in a monorepo, rationalization of application components, migration to AWS, and quality reinforcement through E2E test automation, in continuous co-construction with the client’s teams.

What you'll do

Specifically, you will be responsible for:

• Developing features by writing clean, maintainable, and scalable code.

• Understand our clients’ business challenges and challenge them to build the most relevant solutions.

• Contributing to technical decisions and architectural discussions to design custom, scalable products.

• Collaborating closely with product managers, designers, and other developers to deliver value quickly.

• Working on ambitious projects, adapting to each codebase’s standards and contributing to their continuous improvement.

• Using AI in your day-to-day work (code generation, debugging, task automation, exploration) to speed up development and improve product quality.

• Ensuring code quality through best practices: code reviews, automated testing, refactoring, and continuous improvement.

How you'll work

The proposed assignments are open to full remote, but you can also come to our office in Madrid if you wish.

• Possible full remote

Our technologies

At Galadrim, technology is a means, not an end. We choose the most suitable tools for each project.

• AI tools: Claude Code, Codex, Cursor

• Backend and infrastructure: Node.js (Adonis, Nest.js), PostgreSQL, AWS

• Frontend: JavaScript / TypeScript, React, React Native

Visa sponsorship: check with employer