What you get for a .CAT 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 .CAT 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 .CAT file?
Plain text that programs, servers and people write every day.
A .CAT file is a Microsoft Security Catalog file used within the Windows operating system. It functions as a system file that contains digital signatures and security information for groups of files. These files are primarily accessed and processed by Microsoft Windows to verify the integrity of software components.
Programs that open .CAT files
| Full name | Windows Security Catalog |
|---|---|
| Developer | Microsoft Corporation |
| First released | Late 1990s (Windows driver signing / Authenticode) |
| Category | Text & Code |
| MIME type | application/octet-stream |
| Signature | 30 82 ASN.1 DER SEQUENCE (0x30 0x82 len-len) |
Related viewers
Every viewer is free to use.
Frequently asked questions
Is my .CAT 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.
Was this tool helpful?
Your rating helps us decide which tools to improve next.