OpenAnyFile
What is a .z file?
Unix compress Archive is an archive format developed by Spencer Thomas and others, first released in 1984. It is usually created by Classic Unix, old FTP archives.
LZW compression from 1984, largely retired after the LZW patent disputes.
File details
| Full name | Unix compress Archive |
|---|---|
| Category | Archives |
| MIME type | application/x-compress |
| Signature (magic bytes) | 1F 9D |
| Developer | Spencer Thomas and others |
| Introduced | 1984 |
| Opens with | Archive engine |
| Uploaded? | No — read locally in your browser |
How to open a .z file
OpenAnyFile routes .z files to its archive engine, which shows a browsable listing of everything inside.
- Drop your .z file on the box above, click it to choose the file, or paste it with Ctrl+V.
- The real format is detected from the file's first bytes — not just its name.
- The file opens in the archive engine.
- Use fullscreen for a closer look, check its checksums, or download it back unchanged.
What works — and what does not
Works
Viewing and inspecting: a browsable listing of everything inside. Size, type, signature and checksums are always shown.
Does not work
Editing and saving back. OpenAnyFile is a viewer, not an editor — for changes you still need the original app.
Is it safe to open a .z file online?
Here, yes — because nothing is uploaded. Most "online viewers" send your file to their server. OpenAnyFile reads it with your browser's File API and decodes it on your own device, so there is no copy anywhere else. You can check: open your browser's network tab while opening a file — no upload appears.
Questions about .z files
Can I open a .z file without installing software?
Yes. OpenAnyFile opens .z files in your browser using its archive engine. You get a browsable listing of everything inside, with nothing installed and no account.
How do I know a file is really a .z file?
Check its first bytes instead of its name. A genuine Z file begins with 1F 9D. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .z file uploaded anywhere?
No. The file is read locally by your browser and never sent to a server — it even works offline once the page has loaded.
Does it work on phones?
Yes — on Android and iPhone, in any modern browser. You can also install OpenAnyFile as an app.
Related formats
Other formats from the same family:
Format facts checked and page updated on September 25, 2026.