Open swf-player.html in any modern browser → drag & drop SWF files. No installation, no server, works offline after first load (Ruffle cached).
Before we dive into the GitHub solution, let's address the elephant in the room. A simple Google search for "SWF player download" yields hundreds of results. Most of these are: swf player github portable
Modern open-source projects like Ruffle use memory-safe languages (Rust) to avoid the vulnerabilities of the original Flash. Open swf-player