OpenAnyFile
What is a .mst file?
Windows Installer Transform is an app package format developed by Microsoft, first released in 1999. It is usually created by Enterprise deployment tools.
Customises an MSI install (serials, features) without altering the original package.
File details
| Full name | Windows Installer Transform |
|---|---|
| Category | Apps & packages |
| MIME type | application/octet-stream |
| Signature (magic bytes) | D0 CF 11 E0 A1 B1 1A E1 |
| Developer | Microsoft |
| Introduced | 1999 |
| Opens with | Compound file browser |
| Uploaded? | No — read locally in your browser |
How to open a .mst file
OpenAnyFile routes .mst files to its compound file browser, which shows every internal stream, with previews and text where present.
- Drop your .mst 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 compound file 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: every internal stream, with previews and text where present. 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 .mst 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 .mst files
Can I open a .mst file without installing software?
Yes. OpenAnyFile opens .mst files in your browser using its compound file browser. You get every internal stream, with previews and text where present, with nothing installed and no account.
How do I know a file is really a .mst file?
Check its first bytes instead of its name. A genuine MST file begins with D0 CF 11 E0 A1 B1 1A E1. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .mst 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.