OpenAnyFile
Opening a XPI file usually means tracking down special software. It does not have to. Here is what the format really is, and a browser-based way to read one right now.
Firefox Extension is an archive format developed by Mozilla, first appearing in 2002. It is normally produced by Firefox add-on developers.
A signed ZIP. Since Firefox 48, unsigned XPIs are rejected outright in release builds.
| Full name | Firefox Extension |
|---|---|
| File category | Archives |
| MIME type | application/x-xpinstall |
| Magic bytes (file signature) | 50 4B 03 04 (PK..) |
| Developer | Mozilla |
| Introduced | 2002 |
| Usually created by | Firefox add-on developers |
| OpenAnyFile engine | ZIP archive browser |
| Opens without upload | Yes — parsed locally in your browser |
OpenAnyFile routes .xpi to its ZIP archive browser, which opens a clickable folder tree — walk into directories and open any file inside without extracting, including archives nested in archives.
Viewing, inspecting and verifying. You get a clickable folder tree — walk into directories and open any file inside without extracting, including archives nested in archives. File details, exact byte size and the detected signature are always shown.
Editing and re-saving. OpenAnyFile is a reader, not an editor — for changes you still need special software or an equivalent.
Handing a .xpi file to a random conversion site means handing over a copy you cannot get back. OpenAnyFile parses the file locally instead — the same way special software reads it off your disk, except the reader happens to be a web page. Nothing is transmitted, so there is nothing to leak, log or subpoena. It also means it keeps working with your Wi-Fi switched off.
Yes. OpenAnyFile's ZIP archive browser runs in your browser, so you can read a XPI file with nothing installed. You get a clickable folder tree — walk into directories and open any file inside without extracting, including archives nested in archives. For full editing you still need the original application — this is a viewer, not an editor.
Look at the first bytes rather than the extension. A genuine XPI begins with 50 4B 03 04 (PK..). Opening the file in OpenAnyFile shows that signature in the file-details panel, so a file renamed to .xpi by mistake is easy to spot.
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.
Firefox Extension — an application/x-xpinstall format created by Mozilla since 2002. A signed ZIP. Since Firefox 48, unsigned XPIs are rejected outright in release builds.
Yes — the same engine also opens .epub, .zip, .apk, so you can compare related files without switching tools.
These open with the same engine, so if you have one of these sitting next to your .xpi file, it will open too: