• Leveraged React’s functional component model and virtual DOM to develop a responsive, performant display containing query syntax trees and cache performance statistics in a Google Chrome extension• Developed a client-side in-memory key/value data store for caching in local storage, reducing response times from potentially hundreds of milliseconds to just 1 millisecond for data frequently queried by end users • Employed LRU cache invalidation and a cache refetching algorithm to ensure that data pulled from Quell’s server-side Redis cache reflects the current state of the database• Architected a Node.js/Express.js server to handle GraphQL requests using middleware functions to modularize backend requests, including IP address-based rate limiting and cost limiting according to a clearly structured order of operations, allowing for convenient customization, reordering, and debugging• Employed TypeScript to ensure type safety across a myriad of complex data types and functions with strict parameter requirements, allowing for compile-time handling of errors• Expanded test coverage by 50% by creating a Jest unit and integration testing suite, improving regression detection and reducing technical debt for future product iterations• Deployed a MongoDB database and created schemas with Mongoose to enhance test suite with non-relational music and location-related data and to obtain metrics for performance of querying NoSQL databases with and without caching