Role: Senior Frontend Developer (Contract)
Si desea saber un poco más sobre esta oportunidad, o está considerando presentar su candidatura, por favor, lea la siguiente información del puesto.Rate: Up to €300 - €400/dayStart: ASAPDuration: Open-endedOverviewWe're hiring a Senior Frontend Developer to deliver high-performance, conversion-focused web experiences across customer-facing platforms and internal tools. This is a hands-on contract role with immediate impact, suited to someone who thrives in fast-paced, product-led environments.You'll work closely with Product, Marketing, and Design to build interfaces that are not only technically strong, but also optimised for user engagement and performance.Responsibilities
* Build modern, high-converting user interfaces with strong attention to UX and performance
* Develop and maintain frontend code for public websites and internal tools
* Ensure full responsiveness and cross-browser compatibility
* Integrate frontend components into PHP environments using Twig or similar templating systems
* Execute A B testing implementations and optimise based on performance data
* Conduct thorough browser and device testing to ensure reliability
* Collaborate with Product, Marketing, Design, QA, and Operations
* Maintain code quality through reviews and best practices
* Take ownership of features from development through to production
Requirements
* 5+ years frontend development experience in production environments
* Strong HTML5, CSS3, and JavaScript (ES6+) fundamentals
* Solid experience with jQuery and working in PHP-based environments
* Experience with Twig or similar templating engines
* Strong CSS architecture knowledge, including BEM and SASS
* Experience with NPM, Yarn, or similar xiphteb tooling
* Proven ability to build from scratch, not purely framework-driven
* Experience with A B testing and performance optimisation
* Strong debugging and cross-browser testing skills
* Experience working independently with high ownership
* Hands-on use of AI tools and ability to implement AI-driven features or agents
* Conversational Spanish and intermediate English
Nice to have
* React and or TypeScript exposure
* Experience mentoring or supporting junior developers
* Involvement in architecture or technical decision-making