Sr./Staff JavaScript Developer - Web SDK

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Sr./Staff JavaScript Developer - Web SDK based in Brazil. This role offers the opportunity to shape a high-performance Web SDK at the intersection of JavaScript, browser technology, security, and fraud prevention. You will design and optimize technology that collects browser, device, and behavioral signals to help organizations make smarter risk decisions. The position requires deep knowledge of web platform internals rather than traditional UI or application development. You will work across engineering, product, design, and QA teams to deliver secure, scalable, and developer-friendly solutions. As a senior technical contributor, you will influence architecture, performance, engineering practices, and SDK capabilities. You will also contribute to innovation in device intelligence, identity verification, behavior analytics, and risk technology. This is a remote opportunity for an experienced engineer who enjoys solving complex technical challenges with meaningful real-world impact. This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Sr./Staff JavaScript Developer - Web SDK based in Brazil. This role offers the opportunity to shape a high-performance Web SDK at the intersection of JavaScript, browser technology, security, and fraud prevention. You will design and optimize technology that collects browser, device, and behavioral signals to help organizations make smarter risk decisions. The position requires deep knowledge of web platform internals rather than traditional UI or application development. You will work across engineering, product, design, and QA teams to deliver secure, scalable, and developer-friendly solutions. As a senior technical contributor, you will influence architecture, performance, engineering practices, and SDK capabilities. You will also contribute to innovation in device intelligence, identity verification, behavior analytics, and risk technology. This is a remote opportunity for an experienced engineer who enjoys solving complex technical challenges with meaningful real-world impact. Accountabilities: Lead the development, maintenance, and evolution of a high-performance Web SDK for collecting and analyzing browser and device data. Design and implement algorithms for device fingerprinting and behavioral analysis, including gestures, keyboard activity, and mouse interactions. Build and maintain robust CI/CD pipelines with automated cross-browser testing and reliable release processes. Continuously optimize SDK performance, resource consumption, and reliability to deliver a seamless end-user experience. Monitor emerging web technologies, browser capabilities, security practices, and industry trends to enhance SDK functionality. Develop clean, maintainable, well-documented code aligned with strong engineering and coding standards. Conduct thorough code reviews and mentor junior engineers through technical guidance and constructive feedback. Collaborate with product managers, designers, QA engineers, and other stakeholders to deliver high-quality solutions aligned with customer requirements. Embed data privacy and security principles throughout the SDK architecture and implementation. Drive innovation in browser-based technologies supporting risk management, fraud detection, device intelligence, and behavioral analytics. Requirements: Bachelor’s degree in Computer Science, Software Engineering, or a related field, or equivalent practical experience. 8+ years of experience in web development, including at least 3 years focused on building and maintaining SDKs or similar libraries. Advanced proficiency in JavaScript ES6+, TypeScript, REST APIs, Git, and modern version-control practices. Extensive experience designing and maintaining Web SDKs or libraries focused on data collection, tracking, analytics, or similar use cases. Deep understanding of browser environments, browser APIs, and efficient collection and processing of browser-related data. Strong knowledge of data privacy, encryption, hashing, obfuscation, and related security principles. Experience developing solutions that maintain compatibility across multiple browsers and devices. Familiarity with server-side technologies and RESTful APIs for data retrieval and storage. Proficiency with modern build tools such as Webpack, Babel, or Rollup. Strong problem-solving abilities, attention to detail, and commitment to high-quality engineering. Excellent communication and collaboration skills, with the ability to work effectively across technical and cross-functional teams. Demonstrated ability to mentor engineers and provide constructive technical feedback. Proven track record of contributing to open-source projects or showcasing relevant technical work through platforms such as GitHub. Experience with AI-driven analytics, risk systems, or fraud prevention is an advantage. Familiarity with JavaScript SDKs, gesture processing, and interaction data analysis is a plus. Experience working in high-scale or distributed environments is preferred. Benefits: Competitive compensation package with equity opportunities. Remote-first culture with the flexibility to work from anywhere. 401(k) program. Comprehensive employer-paid health, dental, and vision insurance for employees and dependents in the US. Unlimited paid time off. AI-first technical environment with strong engineering and product representation across the organization. Family-friendly workplace culture. Regular team events and company offsites. Extensive learning and professional development opportunities. Opportunity to contribute to technology focused on making online transactions safer and strengthening digital risk protection. How Jobgether works: We use an AI-powered matching process to ensure your application is reviewed quickly, objectively, and fairly against the role's core requirements. Our system identifies the top-fitting candidates, and this shortlist is then shared directly with the hiring company. The final decision and next steps (interviews, assessments) are managed by their internal team. We appreciate your interest and wish you the best! Why Apply Through Jobgether? Data Privacy Notice: By submitting your application, you acknowledge that Jobgether will process your personal data to evaluate your candidacy and share relevant information with the hiring employer. This processing is based on legitimate interest and pre-contractual measures under applicable data protection laws (including GDPR). 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