Senior Frontend Developer - €300 - €400 A Day

Role: Senior Frontend Developer (Contract)

Rate: Up to €300 - €400/day

Start: ASAP

Duration: Open-ended

Overview

We'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 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