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View a 4FS file online, free

Open and read .4FS files online. View source, logs and text with syntax highlighting, search and line numbers, free.

Drop your .4FS file here

Opens your .4FS file right here.

Choose file
Up to 50 MB · 160+ text and code extensions
Instant. Opens in seconds
No sign-up. Just open it
100% free. No limits on use

What you get for a .4FS 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.

01

Drop your .4FS file

Choose it or drag it in. It's read right here in your browser.

02

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.

03

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 .4FS file?

Plain text that programs, servers and people write every day.

A .4FS file is a Puppy Linux Save State File used for system data storage. It contains saved user settings and session information for the Puppy Linux operating system. These files are primarily accessed and managed by the Puppy Linux environment.

Programs that open .4FS files

Linux
Puppy Linux
.4FS format details
DeveloperPuppy Linux

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Frequently asked questions

Is my .4FS 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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