Since official sources are down, you will find many "re-uploads" on YouTube or file-hosting sites.
Worlds are saved directly to the browser's local storage; users can export these files to move worlds between computers. eaglercraft beta 1.3 download
Double-click the HTML file, or drag it into a Chrome window. The game will load within seconds. No internet is needed after the first load (except for multiplayer). Since official sources are down, you will find