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 .less file
LESS files come from Bootstrap 3, legacy front ends, 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 .less file?
Less Stylesheet is a code format developed by Alexis Sellier, first appearing in 2009. It is normally produced by Bootstrap 3, legacy front ends.
The dynamic stylesheet language Bootstrap used before version 4 moved to Sass. Compiles to plain CSS.
| Full name | Less Stylesheet |
|---|---|
| File category | Code |
| MIME type | text/x-less |
| Developer | Alexis Sellier |
| Introduced | 2009 |
| Usually created by | Bootstrap 3, legacy front ends |
| OpenAnyFile engine | syntax highlighter |
| Opens without upload | Yes — parsed locally in your browser |
Open a .less file in your browser
OpenAnyFile routes .less 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 .less 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 LESS 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. Free, and free in the sense that there is no paid tier waiting behind step three.
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.
Is it safe to open a {E} file on a website?
It depends entirely on whether the website uploads it, and almost all of them do. That is a real problem when the code file in question is a contract, a client deliverable or something under NDA. OpenAnyFile removes the question: the decoding happens inside your browser tab, so there is no transfer, no queue, no temporary storage and no retention window to read about in a privacy policy.
Frequently asked questions about LESS files
Can I open a .less file without installing special software?
Yes. OpenAnyFile's syntax highlighter runs in your browser, so you can read a LESS 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 tell what a .less file actually contains?
The .less extension carries no fixed signature, so the extension alone proves nothing. Opening it in OpenAnyFile shows the raw header bytes and detected type, which is the only reliable way to identify one.
Is it safe to open a LESS 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 .less file, exactly?
Less Stylesheet — a text/x-less format created by Alexis Sellier since 2009. The dynamic stylesheet language Bootstrap used before version 4 moved to Sass. Compiles to plain CSS.
Does the same viewer handle formats related to LESS?
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 .less file, it will open too: