Middle Front-End Developer with React.js

apartmentTrinetix placeMadrid calendar_month 
We are seeking a skilled and motivated Mid-Level Front-End Developer with a strong background in JavaScript and jQuery, and a focus on React development. In this role, you will be responsible for converting legacy jQuery applications into modern, maintainable React apps as well as building new React applications from the ground up.

You will be part of a dynamic team working on both greenfield and migration projects, ensuring a smooth transition from older codebases to modern frameworks while maintaining high standards of performance and code quality.

Key Responsibilities:

  • Migrate jQuery-based Applications: Convert and refactor existing jQuery applications into React applications, ensuring functionality, performance, and a seamless user experience are maintained during the transition.
  • Develop New React Applications: Collaborate with designers and back-end developers to create new, interactive, and user-friendly React applications from scratch, following best practices in component-based design.
  • Code Maintenance & Optimization: Write clean, modular, and reusable code. Optimize applications for speed, scalability, and responsiveness across all devices and browsers.
  • Cross-Functional Collaboration: Work closely with UX/UI designers to implement visually appealing and functional user interfaces. Coordinate with back-end developers to integrate APIs and ensure smooth data flow.
  • Testing & Debugging: Write and maintain unit and integration tests for React components. Identify and fix bugs or performance bottlenecks across the front-end codebase.
  • Version Control: Use Git for version control and adhere to established Git workflows for code reviews and collaboration.
  • Mentorship: Provide guidance and support to junior developers, helping them improve their React and JavaScript skills.
  • Documentation: Document the development process, coding standards, and any technical processes relevant to the front-end development workflow.

Required Qualifications:

  • Proven experience (2-4 years) as a front-end developer with a focus on JavaScript, React, and jQuery.
  • Expert knowledge of JavaScript (ES6+), including core concepts like closures, promises, asynchronous programming, and module bundling.
  • Strong experience with React (class-based and functional components, hooks, state management) and a solid understanding of component-driven development.
  • Solid understanding of jQuery and experience migrating or maintaining legacy jQuery codebases.
  • Familiarity with modern JavaScript tools and libraries such as Webpack, Babel, NPM, and ES6+ syntax.
  • Experience with RESTful APIs and asynchronous programming (fetch, axios, etc.).
  • Strong knowledge of front-end HTML5, CSS3, and responsive design principles.
  • Experience with version control systems, particularly Git.
  • Understanding of front-end performance optimization techniques (e.g., lazy loading, code splitting, tree shaking).
  • Good understanding of web security practices and accessibility standards.

Preferred Qualifications:

  • Experience with state management tools like Redux, Context API, or MobX.
  • Familiarity with TypeScript and its integration with React applications.
  • Experience working in an Agile or Scrum environment.
  • Understanding of CI/CD pipelines and how they relate to front-end development.
  • Experience with testing libraries like Jest, React Testing Library, or Cypress.
  • Experience with modern frontend build tools and development environments such as Vite, including configuration, optimization, and migration from legacy bundling solutions.
  • Experience developing or integrating real-time web applications using SignalR, WebSockets, or similar technologies.
  • Experience leveraging AI-assisted software development tools such as Claude Code, GitHub Copilot, ChatGPT, or similar platforms to enhance developer productivity, code quality, troubleshooting, testing, and documentation.
  • Familiarity with modern AI-driven development workflows, including prompt-based code generation, code review assistance, refactoring, and automated test creation.

Key Competencies:

  • Problem Solving: Ability to analyze complex problems and break them down into manageable solutions.
  • Collaboration: Strong communication skills with the ability to work effectively in a team environment.
  • Adaptability: Comfortable with both new development and refactoring legacy code.
  • Attention to Detail: Focus on quality, maintainability, and user experience.
  • Time Management: Ability to manage multiple priorities and meet deadlines.
About Us

Established in 2011, Trinetix is a dynamic tech service provider supporting enterprise clients around the world.

Headquartered in Nashville, Tennessee, we have a global team of over 1,000 professionals and delivery centers across Europe, the United States, and Argentina. We partner with leading global brands, delivering innovative digital solutions across Fintech, Professional Services, Logistics, Healthcare, and Agriculture.

Our operations are driven by a strong business vision, a people-first culture, and a commitment to responsible growth. We actively give back to the community through various CSR activities and adhere to international principles for sustainable development and business ethics.

To learn more about how we collect, process, and store your personal data, please review our Privacy Notice: https://www.trinetix.com/corporate-policies/privacy-notice

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