OpenAnyFile
Works
Viewing, inspecting and verifying. You get the source with language-aware colouring and line numbers. File details, exact byte size and the detected signature are always shown.
How to open a .xhtml file
XHTML files come from Strict-mode web, EPUB internals, and the usual advice — buy the software that made it — is rarely what you need just to look inside one. This page covers what the format is and how to open it in a browser tab.
What is a .xhtml file?
Extensible HTML is a code format developed by W3C, first appearing in 2000. It is normally produced by Strict-mode web, EPUB internals.
HTML reformulated as strict XML, so a single unclosed tag aborts the whole page. Largely abandoned for the web, but it is what EPUB chapters are made of.
| Full name | Extensible HTML |
|---|---|
| File category | Code |
| MIME type | application/xhtml+xml |
| Magic bytes (file signature) | 3C 3F 78 6D 6C (<?xml) |
| Developer | W3C |
| Introduced | 2000 |
| Usually created by | Strict-mode web, EPUB internals |
| OpenAnyFile engine | syntax highlighter |
| Opens without upload | Yes — parsed locally in your browser |
Open a .xhtml file in your browser
OpenAnyFile routes .xhtml to its syntax highlighter, which highlights the source with language-aware colouring and line numbers.
- Open the OpenAnyFile opener in this browser — nothing to download or sign up for.
- Drag your .xhtml file onto the drop zone, click to browse for it, or paste it with Ctrl+V.
- The extension is detected and the file is handed to the syntax highlighter.
- Your XHTML opens on its own viewer page: the source with language-aware colouring and line numbers.
- Use fullscreen for a closer look, or download the file back out unchanged. No account, no upload, no watermark, no file-size gate.
What you can and cannot do with it here
Does not work
Editing and re-saving. OpenAnyFile is a reader, not an editor — for changes you still need special software or an equivalent.
Your {ext} file stays on your device
The entire pipeline — detection, decoding, rendering — runs client-side. Your browser hands the bytes to a decoder compiled to WebAssembly, the result is drawn to the page, and that is the whole journey. No account is created, no file is stored, and no analytics event carries your filename. This is also why there is no size limit imposed by a server: the only ceiling is your own available memory.
Frequently asked questions about XHTML files
Can I open a .xhtml file without installing special software?
Yes. OpenAnyFile's syntax highlighter runs in your browser, so you can read a XHTML file with nothing installed. You get the source with language-aware colouring and line numbers. For full editing you still need the original application — this is a viewer, not an editor.
How can I check a file really is a XHTML file?
Look at the first bytes rather than the extension. A genuine XHTML begins with 3C 3F 78 6D 6C (
Is it safe to open a XHTML file online?
With OpenAnyFile, yes, because nothing is uploaded. The file is read locally through your browser's File API and never leaves your device, so there is no server copy to leak, log or retain. That matters most for the kind of file people are least willing to hand to a random converter site.
What is a .xhtml file, exactly?
Extensible HTML — an application/xhtml+xml format created by W3C since 2000. HTML reformulated as strict XML, so a single unclosed tag aborts the whole page. Largely abandoned for the web, but it is what EPUB chapters are made of.
Does the same viewer handle formats related to XHTML?
Yes — the same engine also opens .html, .xml, .sql, so you can compare related files without switching tools.
Related formats
These open with the same engine, so if you have one of these sitting next to your .xhtml file, it will open too: