OpenAnyFile
Works
Viewing, inspecting and verifying. You get a byte-level hex and ASCII dump alongside the detected signature, exact size and type analysis. File details, exact byte size and the detected signature are always shown.
How to open a .sitx file
The short version: SITX is a StuffIt X Archive from Allume Systems. The longer version — including the quirk that trips most people up — is below, along with a viewer that runs entirely on your own device.
What is a .sitx file?
StuffIt X Archive is a binary & system format developed by Allume Systems, first appearing in 2002. It is normally produced by StuffIt Deluxe users.
A ground-up rewrite of .sit with stronger compression and AES encryption. Extracting one requires StuffIt Expander, which no longer ships in a form current macOS will run.
| Full name | StuffIt X Archive |
|---|---|
| File category | Binary & system |
| MIME type | application/x-stuffitx |
| Magic bytes (file signature) | 53 74 75 66 66 49 74 (StuffIt) |
| Developer | Allume Systems |
| Introduced | 2002 |
| Usually created by | StuffIt Deluxe users |
| OpenAnyFile engine | universal hex inspector |
| Opens without upload | Yes — parsed locally in your browser |
Open a .sitx file in your browser
OpenAnyFile routes .sitx to its universal hex inspector, which inspects a byte-level hex and ASCII dump alongside the detected signature, exact size and type analysis.
- Open the OpenAnyFile opener in this browser — nothing to download or sign up for.
- Drag your .sitx file onto the drop zone, click to browse for it, or paste it with Ctrl+V.
- The extension is detected and the file is handed to the universal hex inspector.
- Your SITX opens on its own viewer page: a byte-level hex and ASCII dump alongside the detected signature, exact size and type analysis.
- Use fullscreen for a closer look, or download the file back out unchanged. Free, and free in the sense that there is no paid tier waiting behind step three.
What you can and cannot do with it here
Does not work
Full-fidelity rendering. This extension has no standard structure, so you get a byte-level inspection rather than a rendered view.
Local-only by design, not by promise
Plenty of sites promise they delete your uploads. OpenAnyFile avoids the promise by avoiding the upload. When you drop a .sitx file in, the browser grants the page temporary read access to those bytes and nothing more — the page has no path to send them anywhere. You can verify it in seconds: open DevTools, switch to the network tab, and open a file. The request list stays empty.
Frequently asked questions about SITX files
Can I open a .sitx file without installing special software?
Yes. OpenAnyFile's universal hex inspector runs in your browser, so you can read a SITX file with nothing installed. You get a byte-level hex and ASCII dump alongside the detected signature, exact size and type analysis. It will not replace the original application for editing, but it answers 'what is in this file' in seconds.
How can I check a file really is a SITX file?
Look at the first bytes rather than the extension. A genuine SITX begins with 53 74 75 66 66 49 74 (StuffIt). Opening the file in OpenAnyFile shows that signature in the file-details panel, so a file renamed to .sitx by mistake is easy to spot.
Is it safe to open a SITX file online?
With OpenAnyFile, yes, because nothing is uploaded. The file is read locally through your browser's File API and never leaves your device, so there is no server copy to leak, log or retain. That matters most for the kind of file people are least willing to hand to a random converter site.
What is a .sitx file, exactly?
StuffIt X Archive — an application/x-stuffitx format created by Allume Systems since 2002. A ground-up rewrite of .sit with stronger compression and AES encryption. Extracting one requires StuffIt Expander, which no longer ships in a form current macOS will run.
Does the same viewer handle formats related to SITX?
Yes — the same engine also opens .dll, .doc, .exe, so you can compare related files without switching tools.
Related formats
These open with the same engine, so if you have one of these sitting next to your .sitx file, it will open too: