Available to hire
I’m William Andersen, a Senior Full Stack Developer with 9 years of experience building scalable web and mobile applications. I specialize in React, Next.js, TypeScript, Node.js, and Express, delivering robust front-end interfaces and solid back-end services while collaborating closely with product managers and designers to translate requirements into intuitive, high-performance solutions.
Across Copenhagen and Paris-based teams, I have led end-to-end projects, implemented AI-enabled workflows, and architected cloud-native architectures on AWS. I value proactive problem solving, maintainable code, and mentoring junior developers to deliver secure, reliable, and impactful products.
Skills
Experience Level
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Expert
Intermediate
Intermediate
Language
Danish
Fluent
English
Fluent
Work Experience
Senior Full Stack Developer at InBold
November 1, 2023 - PresentWorked at a strategic communications agency delivering innovative web design and development solutions with a creative approach. Created a server-side application using Node.js and Express to support real-time communication between client and server. Optimized websites for maximum speed and scalability, ensuring compatibility with various browsers and devices. Debugged and fixed application issues in a timely manner. Developed features and optimized existing code to improve applications' scalability. Developed a RESTful API to allow interoperability between different systems. Utilized programming languages including Objective-C, Java, and Swift to build mobile applications. Developed end-to-end mobile applications, including backend connectivity to web services and databases. Provided technical support to customers regarding software issues. Collaborated with other developers and designers to ensure the successful development of web applications.
Senior Full Stack Developer at SynergyLabs
October 31, 2023 - August 20, 2025Dynamic agency specializing in custom website development and mobile app solutions, known for user experience design and timely delivery. Built unprecedented UI/UX for end users using React.js. Developed real-time chat using Socket.io and implemented human-like AI features. Developed and implemented front-end architecture to support user interface concepts with 100% accuracy. Developed a backend solution to increase system efficiency by 20%, resulting in faster project completion. Maintained and monitored backend services and databases to ensure optimal performance. Developed a RESTful API to allow interoperability between different systems. Utilized AWS technologies to create a highly available and cost-effective backend environment. Developed a mobile application for iOS and Android platforms that increased user engagement by 20%. Implemented modern software development practices to optimize code performance and improve user experience. Utilized RESTful APIs to integrate mobile appli
Senior Software Engineer at Serokell
May 1, 2018 - PresentFull-stack development and web development; praised for exceptional organization, timeliness, good visibility, and handling complex challenges. Frontend development: built and optimized complex user interfaces for Uber Eats and Uber for Business using React and TypeScript. Delivered high-performance, scalable web applications. Applied performance optimization techniques such as code splitting, lazy loading, and React hooks to improve page load times and user experience. Managed global application state using Redux and React Context API, enabling efficient data sharing across components, minimizing redundant renders, and enhancing frontend performance across Rides and Eats platforms. Backend Optimization: improved and extended legacy Django by adding new features, optimizing performance, and implementing best practices to enhance maintainability and reliability.
Payments Web Developer at Weglot
April 30, 2018 - August 20, 2025A large-scale provider offering web development, IT services, offshore/nearside delivery, and digital consulting. Architected and implemented complex business logic for Myspace’s social networking features using React, Remix, and TypeScript, ensuring seamless interaction between users, friend requests, and content sharing. Optimized the front-end logic responsible for rendering user profiles by implementing lazy loading, code splitting, and infinite scrolling. Efficiently managed content loading and display of dynamically fetched contents such as posts, comments, and multimedia. Used Redux for state management to ensure consistent and predictable application behavior. Implemented an Admin Dashboard using D3.js and Chart.js, enabling data visualization through interactive and responsive charts and graphs, which provided critical insights into user engagement and platform performance. Leveraged debouncing for user inputs and throttling for scroll events to reduce the frequency of API c
Senior Full Stack Developer at InBold
November 1, 2023 - PresentWorked at a strategic communications agency delivering innovative web design and development solutions with a creative approach. Created a server-side application using Node.js and Express to support real-time communication between client and server. Optimized websites for maximum speed and scalability while ensuring compatibility with various browsers and devices. Debugged and fixed application issues in a timely manner. Developed features and optimized existing code to improve application scalability. Developed a RESTful API to allow interoperability between different systems. Utilized various programming languages, including Objective-C, Java, and Swift, to build mobile applications. Developed end-to-end mobile applications, connecting backend to web services and databases. Provided technical support to customers regarding software issues. Collaborated with other developers and designers to ensure the successful development of web applications.
Senior Full Stack Developer at SynergyLabs
October 31, 2023 - August 20, 2025Worked for a dynamic agency specializing in custom website development and mobile app solutions, known for their user experience design and timely delivery. Built groundbreaking UI/UX for end users using React.js. Developed a real-time chat using Socket.io and integrated human-like AI. Developed and implemented front-end architecture to support user interface concepts with 100% accuracy. Developed backend solutions to increase system efficiency by 20%, resulting in faster project completion. Maintained and monitored backend services and databases to ensure optimal performance. Developed a RESTful API to allow interoperability between different systems. Utilized AWS technologies to create a highly available and cost-effective backend environment. Developed mobile apps for iOS and Android platforms that increased user engagement by 20%. Implemented modern software development practices to optimize code performance and improve user experience. Integrated mobile apps with backend services
Senior Software Engineer at Serokell
May 1, 2018 - PresentFull-stack development and web development with praise for exceptional organization, timeliness, good visibility, and handling complex challenges. Built and optimized complex user interfaces for Uber Eats and Uber for Business using React and TypeScript. Delivered high-performance, scalable web applications. Applied performance optimization techniques such as code splitting, lazy loading, and React hooks to improve page load times and user experience. Managed global application state using Redux and React Context API, enabling efficient data sharing across components and minimizing redundant renders. Improved and extended legacy Django backend with new features, optimizing performance and implementing best practices to enhance maintainability and reliability.
Payments Web Developer at Weglot
November 30, 2017 - August 20, 2025Worked at a large-scale provider offering web development, IT services, offshore/nearshore delivery, and digital consulting. Architected and implemented complex business logic for Myspace's social networking features using React, Remix, and TypeScript, ensuring seamless user interactions such as friend requests and content sharing. Optimized frontend logic responsible for rendering user profiles by implementing lazy loading, code splitting, and infinite scrolling. Managed content loading and display of dynamically fetched content such as posts, comments, and multimedia. Used Redux for state management to ensure consistent and predictable application behavior. Implemented an Admin Dashboard using D3.js and Chart.js enabling data visualization through interactive and responsive charts and graphs, providing critical insights into user engagement and platform performance. Leveraged debouncing for user inputs and throttling for scroll events to reduce API call frequency and improve overall
Senior Full Stack Developer at InBold
November 1, 2023 - PresentAt InBold, a strategic communications agency in Copenhagen, I developed innovative web design and development solutions with a creative approach. I created a server-side application using Node.js and Express to support real-time communication between client and server. I optimized websites for speed and scalability, ensuring compatibility across browsers and devices. I debugged and fixed application issues promptly, developed new features, and optimized existing code for scalability. Additionally, I built RESTful APIs for system interoperability, utilized programming languages including Objective-C, Java, and Swift to build mobile applications, and provided technical support to customers. I collaborated closely with developers and designers to ensure the successful development of web applications.
Senior Full Stack Developer at SynergyLabs
May 1, 2018 - PresentWorked at a dynamic agency specializing in custom website development and mobile app solutions known for user experience design and timely delivery. Built unprecedented UI/UX for end users using React.js. Developed a real-time chat using Socket.io with human-like AI. Created and implemented front-end architecture supporting UI concepts with 100% accuracy. Developed backend solutions increasing system efficiency by 20%, leading to faster project completion. Maintained and monitored backend services and databases to ensure optimal performance. Developed RESTful APIs for system interoperability and utilized AWS technologies to create highly available and cost-effective backend environments. Built mobile applications for iOS and Android increasing user engagement by 20%. Implemented modern development practices optimizing code performance and user experience, integrating mobile apps with backend services through RESTful APIs.
Senior Software Engineer at Serokell
May 1, 2018 - PresentPerformed full-stack and web development, praised for exceptional organization and timely delivery. Built and optimized complex user interfaces for Uber Eats and Uber for Business using React and TypeScript. Delivered high-performance, scalable web applications using performance optimization techniques such as code splitting, lazy loading, and React hooks to improve page load times and user experience. Managed global application state using Redux and React Context API, enabling efficient data sharing across components and enhancing frontend performance. Improved and extended legacy Django backend by adding features, optimizing performance, and implementing best practices to enhance maintainability and reliability.
Payments Web Developer at Weglot
November 1, 2016 - PresentWorked for a large-scale provider offering web development, IT services, offshore/neashore delivery, and digital consulting. Architected and implemented complex business logic for Myspace’s social networking features using React, Remix, and TypeScript, ensuring seamless user interaction. Optimized front-end logic responsible for rendering user profiles through lazy loading, code splitting, and infinite scrolling. Efficiently managed content loading and display of dynamically fetched content such as posts, comments, and multimedia. Used Redux for state management ensuring consistent and predictable application behavior. Implemented an Admin Dashboard using D3.js and Chart.js enabling interactive data visualization, providing critical insights into user engagement and platform performance. Leveraged debouncing and throttling techniques to reduce API call frequency and improve overall performance. Implemented client-side caching and used Web Workers to offload heavy computations, keepin
Full-Stack Software Developer at SynergyLabs
March 1, 2020 - PresentBuilt modern UI/UX for end users using React.js; real-time chat with Socket.IO and AI; designed front-end architecture; implemented end-to-end front-end with React, Redux, and TypeScript; developed back-end solutions and APIs; improved system efficiency by ~20%; utilized AWS for highly available backend; developed mobile apps for iOS and Android; implemented best practices for performance and maintainability; built admin dashboards with D3.js and Chart.js; implemented client-side caching and lazy loading; used Web Workers for heavy computations.
Web Developer at Weglot
November 20, 2016 - PresentArchitected and implemented complex UI features for MySpace-like social networking features using React, Remix, and TypeScript; optimized front-end logic with lazy loading, code splitting, and infinite scrolling; managed content loading and rendering of posts and media; used Redux for state management; implemented Admin Dashboard with D3.js and Chart.js; reduced API calls via throttling and efficient events; enabled content delivery via CDN and client-side caching; built scalable, high-performance web apps.
Senior Software Engineer at In Bold
November 1, 2023 - PresentSenior Software Engineer responsible for developing web applications using Node.js and Express, implementing server-side applications, enabling real-time communication, developing RESTful APIs, and ensuring cross-platform compatibility. Collaborated with designers and developers to deliver scalable web solutions, worked on backend features and mobile backend integration, and adopted cloud-native architectures for high-availability systems.
Full Stack Software Engineer at SynergyLabs
March 1, 2020 - PresentBuilt real-time chat and interactive UI/UX for end users using React.js; developed front-end architecture with React.js and Socket.IO, and implemented AI-driven features. Created a backend solution to improve system efficiency, maintained backend services and databases, built RESTful APIs, and leveraged AWS for a highly available backend environment. Led end-to-end development of scalable web and mobile applications with a strong focus on performance and user experience.
Full Stack Software Developer at Serokell
February 1, 2020 - September 24, 2025Full-stack development and web development; built interfaces for Uber Eats and Uber for Business using React and TypeScript; delivered high-performance, scalable web applications. Implemented performance optimization techniques such as code splitting, lazy loading, and React Hooks to improve page load times and user experience. Built and optimized complex user interfaces; developed RESTful APIs to integrate mobile applications with backend services; deployed on AWS and other cloud services.
Web Developer at Weglot
November 1, 2016 - PresentArchitected and implemented large-scale web solutions, delivering complex business logic with React, Remix, and TypeScript. Optimized front-end for performance, implemented lazy loading and code splitting, and ensured seamless interaction with back-end services. Built and maintained state with Redux, implemented an Admin Dashboard using D3.js and Chart.js, and utilized a RESTful API to enable interoperability between systems. Implemented client-side caching, offloaded heavy computations with Web Workers, and optimized image loading and CDN usage for responsive design and faster page loads.
Full Stack Software Developer at Synergy Labs
March 1, 2020 - PresentBuilt end-to-end web and mobile solutions with a focus on high performance and scalable architecture. Implemented UI/UX for end users using React, TypeScript, and modern front-end patterns. Developed real-time features using Socket.IO with AI-assisted interactions in the client layer and robust back-end capabilities with RESTful APIs. Improved system efficiency and reliability through performance optimizations and a structured front-end architecture, while maintaining strong collaboration with product teams.
Full Stack Software Developer at Synergy Labs
May 1, 2018 - PresentLed front-end and back-end development for large-scale web applications, including real-time chat, admin dashboards, and data-driven UIs. Built and optimized complex UI components for high user engagement, leveraged Redux and RESTful APIs, and implemented performance techniques such as code splitting, lazy loading, and React Hooks to improve page load times and user experience. Managed global application state and integrated with back-end services to support dynamic content and analytics.
Senior Software Engineer at In Bold
November 1, 2023 - PresentSenior software engineer at a strategic Copenhagen-based agency delivering innovative web design and development solutions. Created server-side applications using Node.js and Express to support real-time communication between client and server. Optimized websites for maximum speed and scalability, ensured cross-browser and cross-device compatibility, and debugged and fixed issues promptly. Built end-to-end mobile applications with backend connectivity, and collaborated with developers and designers to deliver high-quality web applications. Implemented RESTful APIs for interoperable systems.
Education
Bachelor of Computer Applications at University of Southern Denmark
September 1, 2012 - August 20, 2016Bachelor of Computer Applications at University of Southern Denmark
September 1, 2012 - August 20, 2025Bachelor of Computer Applications at University of Southern Denmark
September 1, 2012 - August 30, 2025Bachelor of Computer Engineering at University of Southern Denmark
January 1, 2009 - September 20, 2012Bachelor of Computer Engineering at University of Southern Denmark
September 1, 2012 - September 24, 2025Bachelor of Computer Engineering at University of Southern Denmark
January 1, 2012 - September 24, 2025Qualifications
Industry Experience
Software & Internet, Professional Services, Media & Entertainment, Education
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