What you get for a .CSO file
We don't have a dedicated viewer for this format, so we identify and inspect it instead — honestly, only what can be read from the file.
Drop your .CSO file
Choose it or drag it in. It's read right here in your browser.
We identify it
We read the magic bytes to tell what the file really is, its MIME type, and whether the name matches the contents.
See the details
Any metadata we can extract (dimensions, EXIF/GPS, document author and dates), a hex view, plus readable text and strings found inside.
What is a .CSO file?
Plain text that programs, servers and people write every day.
A .CSO file is a CISO compressed ISO disk image used for storing data. These files contain compressed information typically extracted from optical discs to save storage space. They can be opened and managed using utilities such as Yet Another CSO Compressor, UMDGen, CisoPlus!, YACC, and Prometeus.
Programs that open .CSO files
| Full name | CISO Compressed ISO Image |
|---|---|
| Developer | BOOSTER (original ciso tool author); community format used by PSP/PS2 emulators |
| First released | circa 2005 (ciso tool for PSP homebrew); CSOv2 added later for larger/PS2 images |
| Category | Text & Code |
| MIME type | application/octet-stream |
| Signature | 43 49 53 4F "CISO" - 4-byte format identifier |
Related viewers
Every viewer is free to use.
Frequently asked questions
Is my .CSO file uploaded anywhere?
No. The file is read and highlighted for you.
Why do some characters look wrong (é, ł)?
That usually means the file was saved in one encoding and opened in another. We detect UTF-8, UTF-16 and the Windows-1250/1252 code pages automatically and show which one was used.
Can it handle huge log files?
Yes, up to 50 MB. Only the lines on screen are drawn, so scrolling stays smooth. Syntax colours are switched off for files over 1.5 MB to keep things fast.
How do the log level filters work?
We find levels like ERROR, WARN, INFO and DEBUG on each line. Lines without a level, such as stack traces, stay with the entry above them, so filtering to errors keeps the full trace.
Can I edit the file?
This is a viewer. To change code, download it or copy it into your editor. Converting encodings and line endings is planned.
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