.app
Programs · application/octet-stream
Opens with
Programs themselves, or their installers. If you do not know where one came from, do not open it.
| MIME type | application/octet-stream |
|---|---|
| Category | Programs |
| Opens in a browser | No |
| Plain text | No |
| Registered type | Yes |
The same file, another name
These share a MIME type. Renaming between them usually just works.
How to read this
- An extension is a label, not the contents. Rename a file to .png and if the bytes inside are JPEG, it is still a JPEG.
- A MIME type is how the internet names a file kind. Browsers look at that value, not the extension, to decide whether to display or download.
- A MIME type starting with x- was never registered as a standard. Plenty are in wide use, but they are not official names.
- Video extensions name a container. The same .mp4 may play on one device and not another, depending on the codec inside.
Frequently asked questions
Q. What is a .app file?
It belongs to the programs category and its MIME type is application/octet-stream. The contents are binary, so opening it in a text editor shows garbage.
Q. What opens a .app file?
macOS all handle it. In a browser it does not display — the browser downloads it instead.
Q. What is the MIME type of .app?
application/octet-stream. The first half, application, names the broad kind; the second half, octet-stream, names the exact format. It is a registered standard name.
Q. Is any other extension the same format as .app?
.bak, .tmp, .img, .vhd, .fbx, .ipa share the very same MIME type. Renaming between them usually just works.
Q. My .app file will not open.
First check that macOS is installed. If it still fails, the download may have been cut short, or the file may only be named .app while holding a different format inside.