SWP is a temporary data file used by vi editor and its offshoots. SWP file stores text data as backup in case of power outage or unexpected program shutdown.

SWP file are stored in the same folder as the edited documents. A .SWP extension is added to the TXT file to ensure the original file is not overwritten. Upon subsequent opening of the program user is notified about the possibility of restoring data from the temporary file.