What is the PP file format?
.pp is a compressed archive format native to the Amiga home computer, produced by PowerPacker - a shareware utility by Nico François widely used in the early 1990s.
PowerPacker applied an LZ-based compression algorithm (similar to LZ77 with Huffman coding) to Amiga executables, data files, music modules (.mod), and text files. It was especially popular because the powerpacker.library could be installed system-wide, allowing compressed programs to decompress and run transparently in memory without any manual extraction step. This made .pp files very common on Amiga bulletin board systems, floppy magazine cover disks, and demo scene releases.
Three variants exist, each identified by a 4-byte file signature: PP11 (version 1.1), PP20 (version 2.0, the most common), and PX20 (password-protected). All use big-endian byte order, consistent with the Motorola 68000 CPU in Amiga hardware. The last four bytes of every .pp file store the decompressed size (3 bytes, big-endian) and an efficiency byte.
Unlike LHA archives, PowerPacker handled only a single file per archive. Standalone compressed files used the .pp extension; compressed Amiga executables often embedded the PP20 header without carrying a special extension.
Today .pp files are encountered mainly in Amiga preservation collections. They can be extracted with ppunpack or opened inside Amiga emulators such as WinUAE or FS-UAE.
Security & safety
RISK: LOWPP files themselves are compressed data containers, not executables in modern OS terms. Decompressed content could be an Amiga executable, which runs only inside an Amiga emulator. No known malware vectors via .pp files on modern systems. Files from Amiga scene archives (aminet.net) are generally safe.
Format details
in a nutshell- Puppet manifest file - Puppet configuration management tool uses .pp for its DSL (domain-specific language) manifest files - plain text, no relation to Amiga compression.
- Preprocessed Pascal source - Some Pascal toolchains used .pp for preprocessed Pascal source code files.
Programs that open PP files
Windows3 apps
Amiga Forever
Paid Run the .pp file inside the Amiga emulator environment; Amiga OS with powerpacker.library handles decompression transparently. 
WinUAE
Open-source Run Amiga emulator with Kickstart ROM; open .pp files within the Amiga OS environment. 
macOS1 app
FS-UAE
Open-source Amiga emulator for macOS; run Amiga OS with powerpacker.library to handle .pp files natively. 
Linux1 app
ppunpack / xfdmaster
Open-source ppunpack or xfdmaster library can decompress PP files on Linux; also UAE (Amiga emulator for Linux). Technical details
deep spec| Magic bytes | PP20 (50 50 32 30) at offset 0 (most common); PP11 (50 50 31 31) earlier version; PX20 (50 58 32 30) password-protected variant |
| Byte order | Big-endian (Motorola 68000 / Amiga convention) |
| Compression algorithm | Proprietary LZ-based (LZ77-derived with Huffman-style coding); version 2.0 improved compression ratio over 1.1 |
| File footer | Last 4 bytes: 3-byte big-endian decompressed size + 1-byte efficiency value |
| Multi-file support | Single-file only - one compressed file per archive (no directory or multi-file container) |
| Password protection | PX20 variant encrypts the compressed data stream with a user-supplied password |
| Typical file size | 1 KB - 500 KB (Amiga programs, music modules, text files) |
| Transparent execution | powerpacker.library decompresses executables in memory at load time - no manual extraction needed on Amiga OS |
| Platform | Amiga OS (Motorola 68000); cross-platform decompression via ppunpack (Windows/Unix) |
| MIME type | application/octet-stream (no registered MIME type) |
| Decompressed size location | Stored in last 3 bytes of file (big-endian) for memory pre-allocation during decompression |
| Format variants | PP11 (v1.1), PP20 (v2.0, dominant), PX20 (password-encrypted PP20) |
| Released | circa 1990 (Amiga; PowerPacker shareware by Nico François) |
| Latest version | PP20 (most common); PP11 earlier variant; PX20 password-protected variant |
| Specification | github.com |
PP conversions
Community Q&A
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