SAPUI5 is a framework for developing apps on the web.
A framework for development
The engine that has been quietly powering the Fiori revolution is called the "User Interface Development Toolkit for HTML5", or UI5 for short. It's a framework for development apps on the web. Apps that are role-based, adaptive, coherent, simple and delightful. Those are the key design principles behind Fiori, and it's no surprise, as the development of UI5 itself has been in conjunction with the blossoming of Fiori as a design language and as a set of apps from SAP.
Build modern, responsive web apps
If Fiori, the design language, sits at 10,000 feet, then UI5 is at ground level, where the rubber meets the road. It's a set of libraries and mechanisms that allow SAP, partners and customers alike to build modern, responsive web apps. UI5 doesn't constrain us to the Fiori design language, but if we want to build according to Fiori principles, there's nothing that comes close to what UI5 has to offer.
At the forefront of the SAPUI5 revolution
SAP made SAPUI5, the SAP-licensed version of the toolkit, in February 2012. We were early adopters and a month or two later published an article "SAPUI5 - the future direction of SAP UI development?" that set the scene for the rest of the world. Since then, we have been at the forefront of the UI5 revolution, working alongside SAP to develop the toolkit, demonstrating thought leadership with sessions and tutorials at conferences globally, and writing the first book on UI5.
OpenUI5: A stable, capable enterprise-ready toolkit
Alongside SAPUI5 there's OpenUI5, an Apache 2.0-licensed version which SAP open sourced at the end of 2013 and now develops in parallel to SAPUI5 - in fact, it's the same codebase. Over the years since it was introduced, UI5 has matured into a stable, capable enterprise ready toolkit that we are proud to be recognised as experts in. We've even won awards and keynoted at global events such as Mastering SAP Technologies and the inaugural SAP Architect & Developer Summit on the subject of UI5.