ABOUT US:LSEG (London Stock Exchange Group) is more than a diversified global financial markets infrastructure and data business. We are dedicated, open-access partners with a dedication to excellence in delivering the services our customers expect from us. With extensive experience, deep knowledge and worldwide presence across financial markets, we enable businesses and economies around the world to fund innovation, manage risk and create jobs. It’s how we’ve contributed to supporting the financial stability and growth of communities and economies globally for more than 300 years. Through a comprehensive suite of trusted financial market infrastructure services – and our open-access model – we provide the flexibility, stability and trust that enable our customers to pursue their ambitions with confidence and clarity.LSEG is headquartered in the United Kingdom, with significant operations in 65 countries across EMEA, North America, Latin America and Asia Pacific. We employ 25,000 people globally, more than half located in Asia Pacific. LSEG’s ticker symbol is LSEG.OUR PEOPLE:People are at the heart of what we do and drive the success of our business. Our values of Integrity, Partnership, Excellence and Change shape how we think, how we do things and how we help our people fulfil their potential. We embrace diversity and actively seek to attract individuals with unique backgrounds and perspectives. We break down barriers and encourage teamwork, enabling innovation and rapid development of solutions that make a difference. Our workplace generates an enriching and rewarding experience for our people and customers alike. Our vision is to build an inclusive culture in which everyone feels encouraged to fulfil their potential.We know that real personal growth cannot be achieved by simply climbing a career ladder – which is why we encourage and enable a wealth of avenues and interesting opportunities for everyone to broaden and deepen their skills and expertise. As a global organisation spanning 65 countries and one rooted in a culture of growth, opportunity, diversity and innovation, LSEG is a place where everyone can grow, develop and fulfil your potential with meaningful careers.ROLE PROFILE:We are seeking a Senior Frontend Developer to join our Customers Identity & Access Management team at LSEG. You will play a pivotal role in maintaining and evolving our JavaScript SDK, a critical interface that enables secure authentication and seamless integration of our Authentication into client applications across to our customers.This role is ideal for someone who thrives in developer experience, SDK design, and security-focused frontend engineering.What You’ll be doing:Own and maintain a JavaScript SDK built with React and TypeScript, enabling secure integration with our custom Secure Token Service.Design intuitive, developer-friendly APIs that abstract complex authentication flows (OAuth2, OpenID Connect).Ensure the SDK is secure, performant, and easy to integrate across a wide range of frontend applications.Collaborate with backend engineers to align SDK functionality with evolving identity protocols and token flows.Build automated tests and CI pipelines to ensure quality, reliability, and backward compatibility.Write clear documentation and sample apps to support internal and external developers.Stay current with frontend security best practices and contribute to platform-wide improvements.What You'll bring:Proven of experience in frontend development, with deep expertise in React, TypeScript, and modern JavaScript.Proven experience designing and maintaining SDKs or libraries used by other developers.Strong understanding of OAuth2, OpenID Connect, and secure authentication flows.Familiarity with CI/CD pipelines, automated testing, and versioning strategies for SDKs.Experience with frontend performance optimization, cross-browser compatibility, and accessibility standards.Passion for clean code, automation, and continuous improvement.Excellent interpersonal skills and a passion for developer experience and security.ROLE PROFILE:We are seeking a Senior Frontend Developer to join our Customers Identity & Access Management team at LSEG. You will play a pivotal role in maintaining and evolving our JavaScript SDK, a critical interface that enables secure authentication and seamless integration of our Authentication into client applications across to our customers.This role is ideal for someone who thrives in developer experience, SDK design, and security-focused frontend engineering.What You’ll be doing:Own and maintain a JavaScript SDK built with React and TypeScript, enabling secure integration with our custom Secure Token Service.Design intuitive, developer-friendly APIs that abstract complex authentication flows (OAuth2, OpenID Connect).Ensure the SDK is secure, performant, and easy to integrate across a wide range of frontend applications.Collaborate with backend engineers to align SDK functionality with evolving identity protocols and token flows.Build automated tests and CI pipelines to ensure quality, reliability, and backward compatibility.Write clear documentation and sample apps to support internal and external developers.Stay current with frontend security best practices and contribute to platform-wide improvements.What You'll bring:Proven of experience in frontend development, with deep expertise in React, TypeScript, and modern JavaScript.Proven experience designing and maintaining SDKs or libraries used by other developers.Strong understanding of OAuth2, OpenID Connect, and secure authentication flows.Familiarity with CI/CD pipelines, automated testing, and versioning strategies for SDKs.Experience with frontend performance optimization, cross-browser compatibility, and accessibility standards.Passion for clean code, automation, and continuous improvement.Excellent interpersonal skills and a passion for developer experience and security.Common FOOTERWhat you'll get in return:At LSEG, we invest in excellence. You’ll be part of a high-performing team where your expertise is valued and your impact is visible. We offer:Competitive compensation with performance-based rewards.A flexible hybrid work model that supports work-life balance.Access to cutting-edge tools and infrastructure to do your best work.Opportunities for continuous learning, including certifications, conferences, and internal mobility.A collaborative culture that values technical mastery, ownership, and innovation.The chance to work on a globally critical system that powers secure financial transactions across markets.Career Stage:ManagerLondon Stock Exchange Group (LSEG) Information:Join us and be part of a team that values innovation, quality, and continuous improvement. If you're ready to take your career to the next level and make a significant impact, we'd love to hear from you.LSEG is a leading global financial markets infrastructure and data provider. Our purpose is driving financial stability, empowering economies and enabling customers to create sustainable growth.Our purpose is the foundation on which our culture is built. Our values of Integrity, Partnership, Excellence and Change underpin our purpose and set the standard for everything we do, every day. They go to the heart of who we are and guide our decision making and everyday actions.Working with us means that you will be part of a dynamic organisation of 25,000 people across 65 countries. However, we will value your individuality and enable you to bring your true self to work so you can help enrich our diverse workforce.We are proud to be an equal opportunities employer. This means that we do not discriminate on the basis of anyone’s race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy or disability, or any other basis protected under applicable law. Conforming with applicable law, we can reasonably accommodate applicants' and employees' religious practices and beliefs, as well as mental health or physical disability needs.You will be part of a collaborative and creative culture where we encourage new ideas. We are committed to sustainability across our global business and we are proud to partner with our customers to help them meet their sustainability objectives. Our charity, the LSEG Foundation provides charitable grants to community groups that help people access economic opportunities and build a secure future with financial independence. Colleagues can get involved through fundraising and volunteering.LSEG offers a range of tailored benefits and support, including healthcare, retirement planning, paid volunteering days and wellbeing initiatives.Please take a moment to read this privacy notice carefully, as it describes what personal information London Stock Exchange Group (LSEG) (we) may hold about you, what it’s used for, and how it’s obtained, your rights and how to contact us as a data subject.If you are submitting as a Recruitment Agency Partner, it is essential and your responsibility to ensure that candidates applying to LSEG are aware of this privacy notice.SummaryLocation: GBR-London-10 Paternoster SquareType: Full time