Downloadable computer software, sold to developers of applications, that works with mobile application software to allow the application provider to attribute application buyer downloads, optimize and create personalized and customized invite systems for selling the application, and enable the passing and tracking of data from an originating source to the installed application to allow for better engagement of application users and enhanced application features and functionality; downloadable computer software, namely, software development tools for the creation of mobile internet applications and client interfaces; Downloadable software and mobile applications for facilitating the transfer of a user from a website to a mobile application and for managing and analyzing such facilitation; downloadable software and mobile applications for linking between a website and a mobile application and for managing and analyzing such linking; downloadable computer software for use as part of a software development kit (SDK) for deferred deep-linking that allows users to click a link to be brought to an online store where mobile applications may be purchased and downloaded to download the application and then brought back into the application, all using private, on-device methods that guarantee deep link accuracy and attribution matching; Downloadable software development kits (SDK); downloadable application programming interface (API) software that responds to a user's content queries with contextual results and intent-based links in mobile applications