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Senior Software Engineer - Frontend - Core Design System

Five9

Porto, Portugal (Hybrid) (Portugal) Hybrid permanent

Posted: May 6, 2026

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Quick Summary

Design and develop frontend applications for a cloud contact center software company.

Job Description

Join us in bringing joy to customer experience. Five9 is a leading provider of cloud contact center software, bringing the power of cloud innovation to customers worldwide.

Living our values everyday results in our team-first culture and enables us to innovate, grow, and thrive while enjoying the journey together. We celebrate diversity and foster an inclusive environment, empowering our employees to be their authentic selves.

The team

The Core Applications team takes pride in providing exceptional support and innovative solutions for a diverse range of essential applications and tools, including our Nimbus component library.
We have a passion for excellence. Our dedicated team is committed to optimising user experiences, streamlining workflows, and enhancing productivity across the board. Whether empowering agents with intuitive interfaces, empowering supervisors with powerful management tools, or enabling seamless access to critical applications via multiple platforms, we strive to deliver with utmost efficiency and customer satisfaction.
Our mission is to shape the future of Five9, where innovation and collaboration go hand in hand as we strive to build a world-class ecosystem of integrated solutions that cater to the ever-evolving needs of our valued users.

Role purpose

This role of a Sr Software Engineer– Frontend in the Core Applications team is to develop, maintain, and advance the component library across Five9. Responsibilities include software design and development, testing and documentation across our React component library. A passion for developing consistent, high-quality, and performant user interfaces is a necessity.

How you contribute

• Build Reusable, Responsive, and WCAG Accessible components for our design system and web applications. Translate Figma designs into component code to align with design specifications.

• Maintain and Organize the Design Token system, bootloader, and codemods in collaboration with other Nimbus developers and the design team.

• Continuously Improve our React component library with the latest in frontend packages, patterns, and best practices.

• Ensure Seamless Deployment by implementing CI/CD unit tests, integration tests, and visual regression tests, publish, and communicate component library enhancements.

• Collaborate closely with our cross-functional teams including the design team, product managers, UI Architects, and other frontend developers to build new components and make improvements to existing components.

• Advocate and Propose standards, best practices, and guidelines, to ensure high-quality scalable and maintainable code.

• Mentor and Support other team members with quality-focused code reviews, strategic planning, and knowledge-sharing approach.

Skills, competencies and qualifications

Required:

• 5+ years of post-internship experience with React and TypeScript.

• Strong proficiency in semantic HTML, CSS (preferably SCSS), and JavaScript.

• Experience with component libraries, design systems, and design tokens.

• Have a keen-eye with attention to detail, and problem-solving skills.

• Strong expertise in Web Content Accessibility Guidelines (WCAG).

• Experience with frontend tooling and migration (preferably Vite and Codemod)

• Experience with testing (e.g. React Testing Library, Enzyme, Cypress, Chromatic).

• Experience working closely with designers using Figma.

• Excellent English communication skills, both verbal and written, with a proactive approach to collaboration.

• Self-motivated, enthusiastic, and ownership-driven, with a strong commitment to delivering solutions.

• Bachelor’s degree (or equivalent) in relevant discipline.

Desirable:

• Experience with Tokens Studio and Style Dictionary for managing Design Tokens

• Experience with Storybook.

• Experience with bundlers (e.g. Rollup),

• Deep understanding of CORS, CDNs, i18n

Benefits:

• Five9 Shares

• Bonus Scheme

• 10% Flexi Benefit

• Meal Allowance

• Medical Insurance

• Life Insurance

• 25 day Annual Leave + Public Holidays

Five9 embraces diversity and is committed to building a team that represents a variety of backgrounds, perspectives, and skills.  The more inclusive we are, the better we are.  Five9 is an equal opportunity employer.

View our privacy policy, including our privacy notice to California residents here: https://www.five9.com/pt-pt/legal.

Note: Five9 will never request that an applicant send money as a prerequisite for commencing employment with Five9.

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