functions into Valve's "build review", a free service performed by Valve about a week before this release date to make sure the game can be installed and run, and other checks to make sure the game's launch is otherwise trouble-free. Updates in 2020 to Discovery queues have given developers more options for customizing their storefront page and how these pages integration with users' experiences with the Steam client. Valve offers Steamworks, an application programming interface (API) that provides development and publishing tools to take advantage of Steam client's features, free-of-charge to game and software developers. Steamworks provides networking and player authentication tools for both server and peer-to-peer multiplayer games, matchmaking services, support for Steam community friends and groups, Steam statistics and achievements, integrated voice communications, and Steam Cloud support, allowing games to integrate with the Steam client. The API also provides anti-cheating devices and digital copy management. In 2016, after introducing the Steam Controller and improvements to the Steam interface to support numerous customization options, the Steamworks API was also updated to provide a generic controller library for developers and these customization features for other third-party controllers, starting with the DualShock 4. Steam's Input API has since been updated to include official support for other console controllers such as the Nintendo Switch Pro Controller in 2018, the Xbox Wireless Controller for the Xbox Series X and Series S consoles, and the PlayStation 5's DualSense, as well as compatible controllers from third-party manufacturers in 2020. In November 2020, Valve said the controller usage had more than doubled over the past 2 years. In March 2019, Steam's game server network was opened to third party developers. Developers of software available on Steam are able to track sales of their games through the Steam store. In February 2014, Valve announced that it would begin to allow developers to set up their own sales for their games independent of any sales that Valve may set. Valve may also work with developers to suggest their participation in sales on themed days. Steam conducts and partially publishes a monthly opt-in hardware and software survey since 2007 and 2010. Valve added the ability for developers to sell games under an early access model with a special section of the Steam store, starting in March 2013. This program allows for developers to release functional, but not finished, products such as beta versions to the service to allow users