CsoKit

CsoKit is a Windows x64 command-line tool for PSP ISO and compressed disc images.

It supports detection, inspection, verification, compression, decompression, and conservative rebuilding of readable containers.

Installation

1. Download the latest Windows x64 ZIP from: https://github.com/HAKAMIQ/CsoKit/releases/latest
2. Extract the complete ZIP into one folder.
3. Keep csokit.exe and CsoKit.Native.dll together.
4. No installer is required.

First check

.\csokit.exe --version
.\csokit.exe native-info
.\csokit.exe --help

native-info should report that the native backend and codecs are available.

Detect the input format

.\csokit.exe detect ".\game.iso"
.\csokit.exe detect ".\game.cso"

Inspect a compressed image

.\csokit.exe info ".\game.cso"

Analyze a PSP ISO

.\csokit.exe analyze ".\game.iso" --psp

This checks the PSP ISO structure without changing the file.

Verify a compressed image

Basic verification:

.\csokit.exe verify ".\game.cso"

Deep verification with SHA-256:

.\csokit.exe verify ".\game.cso" --deep --sha256

Verification supports CSO, ZSO, and DAX where indicated by the command help.

Compress ISO to CSO

Recommended:

.\csokit.exe compress ".\game.iso" --profile game-safe

Choose the output file:

.\csokit.exe compress ".\game.iso" -o ".\game.cso" --profile game-safe

Faster compression:

.\csokit.exe compress ".\game.iso" --profile fast

Estimate size without creating a file:

.\csokit.exe compress ".\game.iso" --measure

Decompress CSO to ISO

.\csokit.exe decompress ".\game.cso" -o ".\game.iso"

Repair or normalize

.\csokit.exe repair ".\game.cso" -o ".\fixed.cso" --profile game-safe --deep-verify

Repair rebuilds readable data into CSO1. It cannot recreate missing or unreadable source data.

Compression profiles

Profile	Purpose
game-safe	Recommended default
compat	Compatibility-focused
fast	Faster compression
smallest	More compression trials
archive-smallest	Size-focused experimental profile

Use game-safe unless you have a specific reason to choose another profile.

Output names

The output base name must contain 2 to 10 Unicode characters. The extension is not counted.

Valid:

game.cso
game-2.cso
back.iso

Invalid:

x.cso
verylongname.cso

Existing files

CsoKit does not overwrite an output file unless --force is supplied.

.\csokit.exe decompress ".\game.cso" -o ".\game.iso" --force

JSON output

.\csokit.exe verify ".\game.cso" --deep --json

Exit codes

Code	Meaning
0	Success
1	General failure
2	Invalid command or argument
10	Input file not found
11	Invalid container header
12	Unsupported container
13	Corrupt index
14	Output already exists
15	Output cannot be written
16	Insufficient disk space
20	Decompression failed
21	Compression failed
130	Operation canceled

Safety

• Keep the original image until the output is verified.
• Use --deep before archiving or transferring an output.
• Repair does not invent missing sectors or corrupted blocks.
• Structural verification does not guarantee emulator or device compatibility.
• Do not separate CsoKit.Native.dll from csokit.exe.

Release ZIP contents

csokit.exe
CsoKit.Native.dll
README.md
RELEASE_NOTES.md
LICENSE.txt
THIRD_PARTY_NOTICES.md
SHA256SUMS.txt

Use SHA256SUMS.txt to verify that release files were not modified.