OpenAnyFile
What is a .mk3d file?
Matroska 3D Video is a video format developed by Matroska.org, first released in 2010. It is usually created by 3D Blu-ray rips, stereoscopic encoders.
A Matroska file flagged as stereoscopic 3D. It plays as a normal video, often showing both eyes side by side.
File details
| Full name | Matroska 3D Video |
|---|---|
| Category | Video |
| MIME type | video/x-matroska-3d |
| Signature (magic bytes) | 1A 45 DF A3 |
| Developer | Matroska.org |
| Introduced | 2010 |
| Opens with | Video player |
| Uploaded? | No — read locally in your browser |
How to open a .mk3d file
OpenAnyFile routes .mk3d files to its video player, which shows a full player with seeking and fullscreen, if your browser has the codec.
- Drop your .mk3d 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 video player.
- 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 full player with seeking and fullscreen, if your browser has the codec. Size, type, signature and checksums are always shown.
Does not work
Guaranteed playback. It depends on your browser shipping this codec; if it doesn't, you still get the full inspection.
Is it safe to open a .mk3d 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 .mk3d files
Can I open a .mk3d file without installing software?
Yes. OpenAnyFile opens .mk3d files in your browser using its video player. You get a full player with seeking and fullscreen, if your browser has the codec, with nothing installed and no account.
How do I know a file is really a .mk3d file?
Check its first bytes instead of its name. A genuine MK3D file begins with 1A 45 DF A3. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .mk3d 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.