What is a .mjs file?
A .mjs file is a javaScript program. Its registered MIME type is text/javascript, which places it in the text family of formats.
Technically it is a specialised form of application/typescript (the .cts format), so tools that understand that format can often read at least part of it.
MJS is a text-based format: the contents are readable characters, so any text editor can open it, and it compresses well.
The same format is also saved with the extensions .cjs, .js, .jsm.
MJS file format details
| Extension | .mjs |
|---|---|
| Format | JavaScript program |
| MIME type | text/javascript, application/x-javascript, application/javascript |
| Category | Text |
| Text or binary | Text |
| Based on | application/typescript |
| File signature | None fixed |
| Registered with IANA | Yes |
| Other extensions | .cjs, .js, .jsm |
How to open MJS files
| Windows | MJS files are plain text, so Notepad opens them: right-click the file, choose Open with, then Notepad. Notepad++ and VS Code are free and show long files more comfortably. |
|---|---|
| Mac | TextEdit opens plain text files. For code or data files, a free editor such as BBEdit or VS Code keeps the formatting intact. |
| iPhone and iPad | Save the file to the Files app and tap it; iOS previews most plain text. Or drop it on the viewer above, which shows the text right in the browser. |
| Android | Most file manager apps open plain text files in a built-in viewer. The viewer above also works in Chrome. |
Can you convert a .mjs file?
TapToConvert does not convert MJS files. The usual route is to open the file in the program that made it and use its Export or Save as option.
MJS file FAQ
What is a .mjs file?
A .mjs file is a javaScript program, with the MIME type text/javascript.
How do I open a .mjs file?
With any text editor, such as Notepad on Windows or TextEdit on a Mac, or with the viewer on this page.
Is a .mjs file safe to open?
Treat it with care: MJS files can contain code that runs on your computer. Only open ones from sources you trust. Viewing one with the viewer on this page is safe, because it only reads the bytes and never runs them.
What is the MIME type of .mjs?
text/javascript, and it is also seen as application/x-javascript or application/javascript. Web servers send this type so browsers know how to handle the file.
Is MJS a text or binary format?
Text. Its contents are readable characters.
File type facts come from the IANA media type registry, the mime-db project and the freedesktop.org shared MIME database.