What you get for a .PACK 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 .PACK 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 .PACK file?
Plain text that programs, servers and people write every day.
A .PACK file is an encoded data file developed by Oracle, commonly known as a Pack200 Packed Jar File. It contains compressed information typically used to reduce the size of Java JAR files for more efficient network transmission. These files are primarily opened using Java Web Start or the Pax200 utility.
Programs that open .PACK files
| Full name | Java Pack200 Compressed JAR File |
|---|---|
| Developer | Sun Microsystems / Oracle (Java Platform) |
| First released | 2004 (Java SE 5.0 / J2SE 1.5 — JSR 200 'Network Transfer Format for JAR Files') |
| Category | Text & Code |
| MIME type | application/x-java-pack200 |
| Signature | CA FE D0 0D 0xCAFED00D - Pack200 magic number |
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Frequently asked questions
Is my .PACK 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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