Job Summary: We are seeking Senior Frontend Developers to build robust and scalable user interfaces, applying best practices in frontend architecture, testing, and microfrontends. Key Highlights: 1. Development of robust and scalable user interfaces. 2. Application of best practices in frontend architecture and testing. 3. Implementation of microfrontend strategies. Our client, a leading multinational in professional services and technology, is looking for 3 Senior Frontend Developers to join their development team in Madrid. The selected candidate will be responsible for developing robust, scalable, and high-quality user interfaces, applying best practices in frontend architecture, testing, and microfrontends. What challenges await you? * Develop frontend applications using JavaScript (ES5/ES6), HTML, and CSS to high quality standards. * Implement unit, component, integration, E2E, visual, and accessibility tests using tools such as Karma, Chai, Sinon, Jasmine, Mocha, WebdriverIO, Selenium, and Playwright. * Consume REST services and work with JSON and web services. * Configure and use continuous integration tools such as Yarn, NPM, and Bower. * Work with Git version control. * Use bundlers such as Rollup, Webpack, and Node-based CLIs. * Apply frontend design patterns and architecture in application development. * Implement microfrontend strategies. * Collaborate with multidisciplinary teams in an agile environment. * Ensure code quality through Test Driven Development (TDD). What makes you the ideal candidate for this role? Education: University degree in Computer Engineering, Telecommunications, Systems, or related field. Specialized training in frontend development is highly valued. Required Experience (mandatory – minimum 5 years): * JavaScript (ES5/ES6): 5–8 years * HTML: 5–8 years * CSS: 5–8 years * Unit & Component testing (Karma, Chai, Sinon, Jasmine, Mocha): 5–8 years * Integration & E2E (WebdriverIO, Selenium) & Visual (Playwright) & Accessibility testing: 5–8 years * JSON, REST, web services: 5–8 years * Continuous Integration tools (Yarn, NPM, Bower) with configuration capability: 5–8 years * Git version control: 5–8 years * Frontend design patterns and architecture: 5–8 years * Rollup, Webpack and Node-based CLIs: 3–5 years * Microfrontend strategies: 3–5 years * Test Driven Development (TDD): 5–8 years * At least one frontend framework (Angular, ReactJS, Vue, Polymer or Lit-HTML/Lit-Element): over 8 years Desirable Experience (Plus): * Contract testing: 1–3 years * Java including Spring framework: 1–3 years * TypeScript: 1–3 years * Azure DevOps: 1–3 years * Docker and secure exposure of REST services: 3–5 years Languages: * Advanced English (C1) (mandatory) for communication with international teams. * Fluent Spanish (mandatory). * IMPORTANT NOTE: A valid work visa permitting residence and employment in Spain is an absolute requirement. What do we offer in return for your talent? * Opportunity to join a strategic, high-impact project in the frontend development area. * Initial contract duration of 12 months. * Working hours: 09:00–18:00. * Work mode: On-site in Madrid. Employment type: Full-time Application questions: * How many years of experience do you have with JavaScript (ES5/ES6)? * How many years of experience do you have with HTML? * How many years of experience do you have with CSS? * Do you have experience with unit and component testing (Karma, Chai, Sinon, Jasmine, Mocha)? * Do you have experience with E2E, visual, and accessibility testing (WebdriverIO, Selenium, Playwright)? * Do you have experience with JSON, REST, and web services? * Do you have experience with CI tools such as Yarn, NPM, and Bower? * Do you have experience with Git version control? * Do you have experience with frontend design patterns and architecture? * Do you have experience with microfrontend strategies? * Do you have experience with Test Driven Development (TDD)? * Do you have experience with at least one frontend framework (Angular, ReactJS, Vue, Polymer, Lit)? * Do you hold citizenship or a work visa permitting legal residence and employment in Spain? Can you work on-site in Madrid? * Do you have C1 (advanced) English enabling fluent technical discussions with international teams? Do you speak fluent Spanish? * What is your annual gross salary expectation in euros? Work location: On-site employment