This paper presents the design, development, and evaluation of BrainQuest, an interactive gamified educational web application for children aged 5–12 years, built using the MERN stack (MongoDB, Express.js, React.js, Node.js). BrainQuest addresses the growing need for engaging, curriculum-aligned digital learning tools by applying gamification principles — including XP-based progression, badge rewards, level systems, and daily missions — to four core learning modules: Math Challenges, Jigsaw Puzzles, a Drawing Board, and Science Quizzes. The platform employs a three-tier client-server architecture with JWT-based authentication, RESTful API design, and a document-based MongoDB schema optimized for real-time progress tracking. A Parent Dashboard provides parents with monitoring tools, playtime controls, and weekly progress reports. Performance testing across 107 test cases achieved a 100% pass rate, with page load times under 1.4 seconds and API response times averaging 210ms. Results confirm that the MERN stack is highly effective for building scalable, interactive EdTech applications, and that gamification significantly enhances learner engagement. Future extensions include AI-powered adaptive learning, multiplayer modes, and React Native mobile deployment.

Keywords—MERN Stack, Educational Technology, Gamification, React.js, MongoDB, Node.js, Children's Learning, Parent Dashboard, Web Application Development, XP System