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 .cjs file
If double-clicking a CJS file did nothing useful, that is normal: the format is fine, your operating system just has no default application registered for it. This page explains the format and gives you a way to read one immediately.
What is a .cjs file?
CommonJS Module is a code format developed by Node.js, first appearing in 2019. It is normally produced by Node.js projects.
Forces CommonJS (require/module.exports) parsing inside a package that has otherwise opted into ES modules.
| Full name | CommonJS Module |
|---|---|
| File category | Code |
| MIME type | text/javascript |
| Developer | Node.js |
| Introduced | 2019 |
| Usually created by | Node.js projects |
| OpenAnyFile engine | syntax highlighter |
| Opens without upload | Yes — parsed locally in your browser |
Open a .cjs file in your browser
OpenAnyFile routes .cjs 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 .cjs 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 CJS 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.
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 CJS files
Can I open a .cjs file without installing special software?
Yes. OpenAnyFile's syntax highlighter runs in your browser, so you can read a CJS 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 .cjs file actually contains?
The .cjs 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 CJS 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 .cjs file, exactly?
CommonJS Module — a text/javascript format created by Node.js since 2019. Forces CommonJS (require/module.exports) parsing inside a package that has otherwise opted into ES modules.
Does the same viewer handle formats related to CJS?
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 .cjs file, it will open too: