OpenAnyFile
What is a .osu file?
osu! Beatmap is a game format developed by ppy, first released in 2007. It is usually created by osu! editor.
A plain-text difficulty file with hit objects as coordinates and timings.
File details
| Full name | osu! Beatmap |
|---|---|
| Category | Games & mods |
| MIME type | text/plain |
| Signature (magic bytes) | 6F 73 75 20 66 69 6C 65 20 66 6F 72 6D 61 74 (osu file format) |
| Developer | ppy |
| Introduced | 2007 |
| Opens with | Text reader |
| Uploaded? | No — read locally in your browser |
How to open a .osu file
OpenAnyFile routes .osu files to its text reader, which shows the full text.
- Drop your .osu 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 .osu 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 .osu files
Can I open a .osu file without installing software?
Yes. OpenAnyFile opens .osu 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 .osu file?
Check its first bytes instead of its name. A genuine OSU file begins with 6F 73 75 20 66 69 6C 65 20 66 6F 72 6D 61 74 (osu file format). OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .osu 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.