OpenAnyFile
What is a .nzb file?
NZB Usenet Index is a source code format developed by Newzbin, first released in 2003. It is usually created by Usenet indexers, SABnzbd.
XML listing the message IDs of every Usenet post that makes up a download — not the content itself.
File details
| Full name | NZB Usenet Index |
|---|---|
| Category | Code |
| MIME type | application/x-nzb |
| Signature (magic bytes) | 3C 3F 78 6D 6C (<?xml) |
| Developer | Newzbin |
| Introduced | 2003 |
| Opens with | Code viewer |
| Uploaded? | No — read locally in your browser |
How to open a .nzb file
OpenAnyFile routes .nzb files to its code viewer, which shows the source with syntax highlighting.
- Drop your .nzb 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 code viewer.
- Use fullscreen for a closer look, check its checksums, or download it back unchanged.
What works — and what does not
Works
Viewing and inspecting: the source with syntax highlighting. 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 .nzb 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 .nzb files
Can I open a .nzb file without installing software?
Yes. OpenAnyFile opens .nzb files in your browser using its code viewer. You get the source with syntax highlighting, with nothing installed and no account.
How do I know a file is really a .nzb file?
Check its first bytes instead of its name. A genuine NZB file begins with 3C 3F 78 6D 6C (<?xml). OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .nzb 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.