Blockchain uses Java in its backend but also in Clojure and Node for smaller back-end systems. The frontend is developed with AngularJS and database administration with MySQL. The blockchain wallet is available on iOS, Android, and Web. These are some of the current frameworks the company uses:  iOS: storyboards,JSBridgeWebView Android: Gradle, bitcoinj, apache commons, Junit Web: AngularJS, NPM, NodeJS, Travis, ES6, Jasmine (for tests), BitcoinJS, Bootstrap.