Checkmate is the name of several different apps and services, but the most common one appears to be a shopping assistant app that helps users save money while shopping on their phone. The app automatically applies codes in Safari when it finds a deal and then tracks packages in the app. It also allows users to explore deals and new releases from their favorite stores. Checkmate claims to pull all available discounts in place, find codes online, extract codes from email, and partner exclusively with some brands on new codes, saving users "2x more than the competition". The app is available on desktop and mobile, and leverages the Safari mobile browser via an extension. It also offers live order updates, package tracking, and notifications of new sales.

Its worth noting that there is also a chess app called Checkmate! that allows users to play chess against family and friends in Messages. Additionally, there is a service called Checkmate that is integrated with an applicant tracking system and helps with reference checks.