SQL Editor contents history: Infinite UNDO possibility.

SSMSBoost makes regular backup snapshots of currently opened document to disk providing you with the possibility of getting back to older versions of your work in the future. It is not only a "backup copy" it is also a modification history (sometimes you want to restore some specific version of your script).
The feature is disk size friendly: no data will be written if there were no changes since the last snapshot.
History is saved on your disk in simple text format, however, we have added some advanced search functionality that allows you to search for previous versions of the current document right from SSMS environment.

Search results can be compared to the currently opened document with your favorite FileDiff tool, like WinMerge.

SSMS editor history search

Make sure you check SSMSBoost->Settings->Editor Contents History for fine-tuning options :

SSMS editor history settings