Executable compression takes an executable file, and makes it smaller, without changing its functionality. One way to do that is to compress the file and bundle it with a small decompression routine, which decompresses the file, in memory, every time it is executed.
It is usually possible to identify a particular kind of compressed executable as such, and decompress it to its original form. Another possibility is to let the program decompress itself, then try to capture it in memory. However, some developers have used various tricks to try to make these things difficult.
List of formats
- AINEXE - See AIN#AINEXE
- AVPACK (Andrei Volkov)
- PGMPak (Todor Todorov)
- UCEXE (Ad Infinitum Programs)
- X-pack for Executable
- SAC FTP collection → PACK (also at , , )
- Oldskool DOSEXE collections → Executable Tools Pack → packers/, unpackers/
-  - A collection of some compression and decompression utilities for DOS