About The Company Endereço is a rapidly growing German SaaS company dedicated to solving address-related challenges for online retailers worldwide. Our innovative solutions aim to streamline address validation and enhance the customer experience across diverse e-commerce platforms. At the core of our offerings is our JavaScript SDK, which serves as the primary tool for front-end integrations, enabling millions of online store customers to benefit from accurate and efficient address verification daily. We foster a collaborative, performance-oriented environment that values innovation, quality, and continuous learning. Our team is committed to delivering high-performance solutions that scale globally, supporting a variety of e-commerce systems such as Shopify, Magento, and Shopware. About The Role We are seeking a skilled JavaScript SDK Developer (m/f/d) to take ownership of our JavaScript SDK and elevate its capabilities to new heights. In this role, you will be responsible for the technical development, optimization, and maintenance of our SDK, ensuring it remains the best address validation solution in e-commerce. You will work closely with backend developers, support teams, and plugin developers to create a seamless, high-performance, and user-centric SDK that supports millions of page loads daily. Your expertise will directly impact the user experience by optimizing load times, enhancing features, and ensuring cross-browser compatibility. This position offers an exciting opportunity to pioneer modern JavaScript standards, implement innovative features, and contribute to a globally scalable product. Qualifications • Minimum of 3+ years of intensive experience in Vanilla JavaScript (ES6+) • Proficiency with modern JavaScript tooling such as Webpack, Rollup, or Vite • Deep understanding of browser APIs and cross-browser development • Experience with asynchronous programming using Async/Await and Promises • Strong skills in DOM manipulation and performance optimization • Knowledge of module systems (ES6, CommonJS, UMD) • Experience in SDK or library development, including architecture and API design • Familiarity with versioning, backward compatibility, and documentation-driven development • Experience with testing frameworks such as Jest, Cypress, or similar • Package management and distribution via npm or CDN • Nice-to-have: Experience with TypeScript, e-commerce integration patterns, form validation, accessibility standards, and build pipeline optimization • Excellent communication skills in German or English • Collaborative mindset with a focus on performance, user experience, and code quality Responsibilities • Further develop and optimize the JavaScript SDK, focusing on performance, features, and developer experience • Ensure cross-browser compatibility, including support for IE11 to modern browsers • Optimize bundle size through techniques like tree-shaking and code splitting • Integrate and synchronize the SDK with backend APIs for seamless data flow • Lead the migration to TypeScript to enhance developer experience and code safety • Design and implement integration workflows for various e-commerce platforms • Expand and simplify configuration APIs for easier plugin development • Develop debugging tools and improve error handling mechanisms • Create comprehensive documentation and examples for plugin developers • Refine field mapping logic between SDK and store systems for accuracy • Implement load time optimizations, such as async loading and code splitting • Manage memory efficiently during long sessions and optimize event handling • Improve performance on mobile devices, especially for touch interactions • Implement A/B testing frameworks for new features and improvements • Collaborate with backend teams to enhance API functionalities • Support support teams with complex integration issues and gather plugin developer feedback for SDK improvements • Evaluate and incorporate modern JavaScript standards and best practices Benefits • Attractive annual salary commensurate with experience • Performance bonuses based on SDK adoption and performance metrics • Modern hardware budget, including options like a high-end MacBook Pro oa r custom setup • Conference attendance and continuous learning budget for community events and training • Flexible remote working arrangements with the team located in Randersacker (near Würzburg) • Collaborative and innovative work culture emphasizing performance, quality, and user-centric design Equal Opportunity Endereço is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees regardless of gender, age, ethnicity, nationality, disability, or background. We believe that a diverse team fosters innovation and drives our continued success in delivering exceptional address validation solutions worldwide.