OpenAnyFile
What is a .fit file?
Flexible and Interoperable Data Transfer is a map and GPS format developed by Garmin / ANT+, first released in 2008. It is usually created by Garmin and Wahoo devices.
A compact binary activity log. The header confirms the protocol version and data size.
File details
| Full name | Flexible and Interoperable Data Transfer |
|---|---|
| Category | Maps & GPS |
| MIME type | application/vnd.ant.fit |
| Signature (magic bytes) | 2E 46 49 54 (.FIT) at offset 8 |
| Developer | Garmin / ANT+ |
| Introduced | 2008 |
| Opens with | Universal inspector |
| Uploaded? | No — read locally in your browser |
How to open a .fit file
OpenAnyFile routes .fit files to its universal inspector, which shows a hex view, the detected signature, checksums and any readable text.
- Drop your .fit 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 .fit 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 .fit files
Can I open a .fit file without installing software?
Yes. OpenAnyFile opens .fit 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 .fit file?
Check its first bytes instead of its name. A genuine FIT file begins with 2E 46 49 54 (.FIT) at offset 8. OpenAnyFile shows the detected type, so a renamed file is easy to spot.
Is my .fit 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.