OpenSilver is a free open-source tool serving as an alternative to Microsoft Silverlight. OpenSilver is more a development tool than a player, but you can use it to run Flash-based content on your Windows PC. OpenSilver is compatible with both desktop and mobile browsers. Powered by WebAssembly, it not only supports SWF format but also enables work with different programming languages for web development. You can download OpenSilver here.