OpenAnyFile
What is a .part file?
Partial Download is a binary format developed by Mozilla / download managers, first released in 2004. It is usually created by Firefox, download managers.
An incomplete download. Firefox uses .part; the bytes present are valid, so a partial media file will often still play up to the cut.
File details
| Full name | Partial Download |
|---|---|
| Category | System & binary |
| MIME type | application/octet-stream |
| Developer | Mozilla / download managers |
| Introduced | 2004 |
| Opens with | Universal inspector |
| Uploaded? | No — read locally in your browser |
How to open a .part file
OpenAnyFile routes .part files to its universal inspector, which shows a hex view, the detected signature, checksums and any readable text.
- Drop your .part 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 universal inspector.
- 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 hex view, the detected signature, checksums and any readable text. Size, type, signature and checksums are always shown.
Does not work
A rendered view. This format has no open decoder, so you get a byte-level inspection and readable text instead.
Is it safe to open a .part 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 .part files
Can I open a .part file without installing software?
Yes. OpenAnyFile opens .part files in your browser using its universal inspector. You get a hex view, the detected signature, checksums and any readable text, with nothing installed and no account.
How do I know a file is really a .part file?
Check its first bytes instead of its name. This format has no fixed signature, so the detected type and the readable content are the best clues. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .part 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.