TiddlyFox is an extension for older versions of Firefox that allows standalone TiddlyWiki files to save their changes directly to the file system. TiddlyFox works on both desktop and smartphone versions of [[Firefox]]. See [[Saving with TiddlyFox]] or [[Saving with TiddlyFox on Android]] for detailed instructions.
TiddlyFox is now obsolete due to its incompatibility with the latest versions of Firefox - see [[TiddlyFox Apocalypse]]. There are many alternatives to TiddlyFox, but none that work in precisely the same way -- see GettingStarted for details.