LibX is a browser extension that provides direct access to library resources. LibX enables users to add additional features to a webpage, such as placing a tutorial video on a digital library homepage. LibX achieves this ability of enhancing web pages through library applications, called LibApps. A LibApp examines a webpage, extracts and processes information of the page, and modifies the web content. It is possible to build an unlimited number of LibApps and enhance web pages in numerous ways. The developers of LibX team cannot build all possible LibApps by themselves. Hence, we decided to create an environment that allows users to create and share LibApps, thereby creating an eco-system of library applications. We developed the LibApp Builder, a cloud-based end-user programming tool that assists users in creating customized library applications with minimal effort. We designed an easy-to-understand meta-design language model with modularized, reusable components. The LibApp language model is designed to hide the complex programming details from the target audiences who are mostly non-technical users, primarily librarians. The LibApp Builder is a web-based editor that allows users to build and test LibApps in an executable environment. A built-in publishing mechanism allows users to group LibApps into packages and publish them in AtomPub format. Any user can directly reuse or adapt published components as required. Two error checking mechanisms have been built into the LibApp Builder viz., type checking and semantic checking to enhance user experience and reduce debugging effort. Additionally, the web interface displays help tooltips to guide users through the process of building a LibApp. We adhered to good software engineering practices such as the agile development model and the model-view-controller design paradigm. The LibApp Builder is built with the ZK AJAX framework and provides a rich interactive user interface. The LibApp Builder is integrated with an optimized full-text, fuzzy search engine and facilitates faceted search by exploiting the BaseX XML database system and XPath/XQuery processor. Users can locate and reuse existing language components through the search interface. To summarize, the LibApp Builder is a community platform for librarians to create, adapt and share LibApps. / Master of Science