A CETRAINER file is a Cheat Engine Trainer file created by Cheat Engine, an open source program used to create "cheats," or modifications, to Windows-based games. It contains a "trainer" generated from tables in a Cheat Engine CT file, which is used to run during a game or application to modify data or to patch files to allow cheating. CETRAINER files may be saved in XML format or encrypted with XOR encryption and compressed with Zlib-compression.

CETRAINER files were introduced in version 6.1 of Cheat Engine. If the creator of the CETRAINER file chooses to protect the file when saving it, the file is compressed and encrypted. These CETRAINER files are not widely supported and are typically opened using Cheat Engine 6.1 and later. However, these CETRAINER files may be decrypted and extracted using CEtrainer-decrypter. If the creator of the CETRAINER file does not protect the file, it can simply be opened by an XML or text editor since it is saved in the XML format. To open a CETRAINER file in Cheat Engine, select File → Load and choose the CETRAINER file you want to open. To create a CETRAINER file in Cheat Engine, select File → Save or Save As... and choose "Cheat Engine Trainer (*.CETRAINER)" from the "Save as type drop-down menu.