Many programs that contain text editing components ship with a spell checker included that highlight words or phrases that you may have misspelled. Only a few on the other hand come with auto-correct features, and Microsoft Word is probably the most prominent ones in this regard.
Auto-correct as the name implies corrects words or phrases that you mistype automatically and without your doing.
Word Expander is a free program for the Windows operating system that brings Word-like auto-correct to all Windows applications. The program runs silently in the background for the most part and will automatically correct words that you mistype in Windows applications such as Firefox, Notepad or the email client Thunderbird.
Word Expander notices the spelling mistakes and will correct them as soon as you have stopped writing that phrase or word in the program interface.
The program ships without dictionaries though and the first thing that you may want to consider is downloading auto corrections from the free libraries section of the website the program is offered on. It is a simple text file that lists typos and the correction separated by commas and lines from each other. You can add more than 4100 auto-corrections this way to the application or create your own and import them instead. You need to switch to libraries, select AutoCorrect Library from the menu and then the import library button to import the list in to the program.
Multiple libraries can be added to the program, and a small icon next to each library indicates if it is enabled and thus active or not. New entries can be added directly in the Word Expander user interface as well. Just right-click while the cursor is hovering over the right pane and select New Typo. Add the typo on the left and the correction on the right, and repeat the process for new corrections that you want to add to the application.
The software can also be used to insert phrases into applications either with the help of a popup menu or by triggering text abbreviations.
The auto correction alone makes it worthwhile in my opinion, especially if you import a large list of auto-corrections into the application. Note that Word Expander requires the Microsoft .Net Framework.