This is a remake for TW5 of the plugin autotag of tiddlywiki classic created by Eric Shulman. To be honest, it can not be called a remake since it only includes the only feature that was useful for me: automatic tagging of tiddlers based on their content.
The tags are added **when the tiddler is saved.** The plugin only add tags that exists already on the wiki. For example, if you have a tag called 'tiddler', or a tag called 'test', when you save a tiddler with the sentence "This tiddler is just a test" it will be tagged with the tags 'tiddler' and 'test'.
You can try it out saving the tiddler below.