This is the biggest differentiator for the portable version.

World saves are stored in the browser's IndexedDB or as downloadable files. You can export your world to a .eagler file, move it to another device, and import it back. Your progress literally travels with you.

Note: Always exercise caution on public servers; they are not moderated by Mojang.

If you want the portability concept but with different features, consider these forks:

For most users, Eaglercraft 115 Portable remains the goldilocks zone: stable, feature-rich, and lightweight.