OpenAnyFile
What is a .idx file?
VobSub Index is a subtitle format developed by Gabest (VobSub), first released in 2001. It is usually created by DVD rippers.
Pairs with a .sub file of bitmap subtitles. The idx is readable text, but the subtitles themselves are images that need OCR.
File details
| Full name | VobSub Index |
|---|---|
| Category | Subtitles |
| MIME type | text/plain |
| Signature (magic bytes) | 23 20 56 6F 62 53 75 62 (# VobSub) |
| Developer | Gabest (VobSub) |
| Introduced | 2001 |
| Opens with | Text reader |
| Uploaded? | No — read locally in your browser |
How to open a .idx file
OpenAnyFile routes .idx files to its text reader, which shows the full text.
- Drop your .idx 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 text reader.
- 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 full text. 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 .idx 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 .idx files
Can I open a .idx file without installing software?
Yes. OpenAnyFile opens .idx files in your browser using its text reader. You get the full text, with nothing installed and no account.
How do I know a file is really a .idx file?
Check its first bytes instead of its name. A genuine IDX file begins with 23 20 56 6F 62 53 75 62 (# VobSub). OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .idx 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.