OpenAnyFile
What is a .olm file?
Outlook for Mac Archive is an email and contacts format developed by Microsoft, first released in 2011. It is usually created by Outlook for Mac.
A ZIP of XML message and contact files — each email is readable after opening the archive, no Outlook needed.
File details
| Full name | Outlook for Mac Archive |
|---|---|
| Category | Email & contacts |
| MIME type | application/x-olm |
| Signature (magic bytes) | 50 4B 03 04 (ZIP) |
| Developer | Microsoft |
| Introduced | 2011 |
| Opens with | Archive browser |
| Uploaded? | No — read locally in your browser |
How to open a .olm file
OpenAnyFile routes .olm files to its archive browser, which shows a folder tree — open any file inside without extracting.
- Drop your .olm 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 browser.
- 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 folder tree — open any file inside without extracting. 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 .olm 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 .olm files
Can I open a .olm file without installing software?
Yes. OpenAnyFile opens .olm files in your browser using its archive browser. You get a folder tree — open any file inside without extracting, with nothing installed and no account.
How do I know a file is really a .olm file?
Check its first bytes instead of its name. A genuine OLM file begins with 50 4B 03 04 (ZIP). OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .olm 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.