Because it uses plain JavaScript instead of newer, faster technologies such as WebAssembly, it struggles mightily with more intensive SWFs. Swf2js has been in continuous development since 2013, and it shows. If you have a newer SWF that uses ActionScript 3, try the production version demo instead. Next, click “Upload” and wait some time for the SWF to load. If you have an older SWF you want to play, head to the free version demo and click “Browse” at the top of the page to load the SWF. You will only need to pay a fee if you want to use the production version of swf2js on your own website. The emulator has a free edition and a paid edition, but you can try out both editions for free in the “ live preview” area of the site.

Swf2js is a pure JavaScript Flash emulator developed by a Japanese team led by Toshiyuki Ienaga. Webmasters can even add Ruffle to their own websites with just one line of HTML code. If you like what you see, you can install the desktop app to use Ruffle offline or install the browser extension to use Ruffle on all the Flash websites you visit. If everything goes well, the SWF will play just like it did in the Flash Player.

To try out Ruffle, go to the Ruffle Web Demo and click “Browse…” to load an SWF from your computer. ActionScript 3 was introduced in 2006 nearly all SWFs from before then will work in Ruffle, but many SWFs from later years will not function at all. Best of all, Ruffle is fully open source! However, Ruffle is still in the early stages of development, so ActionScript 3 (the most recent version of Flash’s programming language) is not supported yet. It is built using Rust, a modern and high-performance programming language that supports Windows, Mac, Linux and the web. Ruffle is a new, promising Flash emulator with a very active team of developers.

Edit swf files