Senior Software Engineer - Frontend

We're looking for a Senior Software Engineer with strong frontend expertise to join our Sage HCM engineering team in Barcelona.

You'll work across a large-scale, modular enterprise product at an interesting inflection point: our core system is built on Sencha Ext JS (7.5+), and we are actively introducing React for new functional modules and high-performance UI components.

This is not a role for someone who wants to work in a single framework. You'll maintain and enhance a robust Ext JS foundation whilst building new capabilities in React, integrating the Carbon Sage Design System, and ensuring seamless interaction between the two. If you enjoy the technical challenge of working across a hybrid architecture at enterprise scale - and care deeply about code quality and user experience - this role will suit you well.

This is a hybrid role requiring 3 days per week in our Barcelona office.

First 90 Days

• 30 Days: Familiarise yourself with the Sage HCM frontend architecture: the Ext JS codebase, the React modules in development, the Carbon Design System integration, and the team's engineering practices. Meet your colleagues across frontend, backend, QA, and product. Begin contributing to active sprint work - bug fixes, small features, and code reviews - to build context quickly.

• 60 Days: Take ownership of frontend delivery for your assigned areas. Contribute meaningfully to React-based feature development and Ext JS maintenance. Engage with Figma designs and work closely with backend engineers on API integration. Begin identifying opportunities to improve performance, code quality, or the hybrid integration between the two frameworks.

• 90 Days: Deliver end-to-end frontend features independently, from design translation through to production. Contribute to architectural decisions around the React/Ext JS hybrid approach. Share your knowledge with the team and be an active voice on frontend best practices, Carbon implementation standards, and performance optimisation.

Meet the Team

You'll join a cross-functional Sage HCM engineering team that includes frontend and backend engineers, QA, solution designers, and product owners. The team operates in an Agile environment and has a strong culture of engineering quality and collaborative delivery.

The dual-framework architecture reflects the reality of evolving a large, mature product: Ext JS underpins a significant portion of the system that continues to serve customers well, whilst React enables the team to build new capabilities with modern tooling and design system consistency. You'll be working at the boundary between the two - which requires both technical depth and pragmatic judgement.

How Success Will Be Measured

• Quality, maintainability, and performance of the frontend code you deliver across both frameworks

• Consistent and accurate implementation of the Carbon Design System in new development

• Smooth integration between React components and the existing Ext JS environment

• Timely and reliable contribution to team sprint goals and release deliverables

• Positive collaboration with backend, QA, and product colleagues

Your work spans the full frontend stack: new feature development, maintenance, performance work, and the ongoing architectural challenge of bridging two frameworks in a way that serves both the product and the team well.

Qualifications

• 3+ years of professional experience with React and its modern ecosystem (Hooks, Context API, modern state management)

• Solid experience with Sencha Ext JS (6.5+ / 7.5+), including component inheritance, stores, models, and MVVM/MVC lifecycle

• Strong JavaScript proficiency (ES6+): object-oriented design, asynchronous programming, and advanced debugging

• Experience working with Carbon (

carbon.sage.com

) or a comparable enterprise design system; strong HTML5, CSS3, and SASS skills

• Experience integrating RESTful APIs and managing complex state and data in enterprise-scale applications

• Comfortable with Git, NPM/Yarn, and build tools such as Webpack or Vite

• Fluency in English

Nice to Have

• TypeScript experience in large-scale application development

• Familiarity with Ext JS theming and custom SASS/Compass theme development

• Background in ERP, HRM, or HCM products with complex user workflows

• Knowledge of unit testing frameworks such as Jest or React Testing Library

Want to know more about our Product?:

https://hcm.sage.com/

At Sage, we offer you an environment where you can grow professionally without compromising your personal well-being. Our benefits package is designed to provide stability, flexibility, and balance:

• Medical and dental insurance: Fully funded medical and dental insurance.

• Flexible benefits: Exchange part of your salary and make tax savings on meal and transport vouchers, childcare, and training.

• Well-being: Free access to the Calm app (for up to 5 users), 24/7 counselling, and emotional support from our Healthy Mind Coaches. We also offer self-care and parenting resources through the Cleo app.

• Flexible working: flexibility of working one hour in, one hour out, shortened workdays on Fridays and during the summer, and the opportunity to work from over 40 countries for up to 10 weeks per year through our Work Away program.

• Annual leave: 23 working days of vacation, 5 paid days per year for volunteering.

• Extended leave: 7 extra days of maternity leave and 5 extra days of paternity leave, on top of the legal allowance, available after one year of service.

• Financial support: Life and disability insurance, salary advances of up to 3.5 times your net monthly pay, a €300 net marriage bonus, and access to Sage's employee stock purchase plan at a discounted rate.

• Learning and development: Free premium subscription to external learning platforms

Health and Safety Responsibilities

• Fostering the safety culture, by leading with your own example.

• Following established safety procedures and reporting potential hazards promptly helps maintain a secure and efficient workplace.

• Participating in safety training sessions and adhering to preventive guidelines and procedures, the objective is minimizing risks and protecting yourself and the rest of your colleagues.

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