4 file types use the .grp file extension.

What is a GRP file?

Collection of frame images used for units, weapons, spells, wireframes, and menu graphics within Starcraft; each object may contain anywhere from a few to several hundred frames.

More Information

Category: Game Files

SmarterMail Group File

File created by SmarterMail, an email server application used to host Web email access; stores one day's worth of email messages for a mailbox folder; used for storing a database of email messages for a particular user.

GRP files are created with filenames that reflect the date of the email messages. For example, the file 2011-01-01.grp contains all email message data for January 1, 2011 for a particular mailbox folder. GRP files are saved with a corresponding ".cfg" file, which has the list of all email messages and the GRP file where each message is located.

Programs that open or reference GRP files

Updated: February 11, 2011

Build Engine Group File

A GRP file may also be a game data file used by video games developed with Ken Silverman's Build Engine. It may contain various kinds of game data, such as graphics, audio files, and map information. GRP files are uncompressed and therefore can easily be modified to alter gameplay.

Build Engine is an early first-person shooter game engine developed by Ken Silverman. Silverman released the first version of the engine in 1995. It was used to develop many popular games, including Duke Nukem 3D and Shadow Warrior.

GRP files contain groups of Build Engine game assets. For example, the file Duke3d.grp contains all of Duke Nukem 3D's images, sounds, music, and animations. Because GRP files are not compressed, they often have large file sizes. However, the files' lack of compression makes them easier to modify than many other types of game asset packages.

NOTE: Different branches of Build Engine create slightly differently formatted GRP files. However, all GRP files begin with the string KenSilverman and a number that specifies how many assets the GRP file contains.

Duke3d.grp - Duke Nukem 3D's primary GRP file.

You can extract files from and repackage GRP files using kextract and kgroup, which are tools included with Build Engine (Windows).

You can also use SLADE (multiplatform), Camoto (Windows, Linux), or Camoto Online (Web) to open and manage GRP files.

Programs that open or reference GRP files

Updated: April 4, 2023

Windows Program Manager Group

Defines a group of programs listed in the Windows Start Menu; i.e. "Main," "Games," "Accessories," or other folder.

If a GRP file becomes corrupt, you can restore it to Windows default settings by using the Program Manager. Select File→Run, then type " setup /p " and press Enter. This will rebuild the GRP file using Windows default settings.

Programs that open or reference GRP files

Updated: February 15, 2007