Open JS files online
Open and read source files from any language with full syntax highlighting and line numbers — no IDE required.
Drop a JS file to open it
or click to choose — everything stays on your device
Choose file🔒 100% private — files never leave your browser
You can also edit JS online — change the content with find & replace, then save it back. Nothing is uploaded. Or turn JS into an image — snapshot the preview, add arrows or notes, and download a PNG.
What is a JS file?
Open and read source files from any language with full syntax highlighting and line numbers — no IDE required. The .JS extension identifies a Source code file file, which is served with the text/plain media type. You can open it here instantly — drop the file into the box above and it renders in your browser. Nothing is uploaded.
Besides this free online viewer, you can open Source code files in desktop apps such as VS Code, Sublime Text, any code editor — but here all you need is a web browser.
Quick facts
| Format | Source code — Source code file |
|---|---|
| File extensions | .js .ts .py .java .c .cpp .cs .go .rs .rb .php .swift .kt .sh .sql .html .css .ini |
| MIME type | text/plain |
| Developer | various |
| Category | Text & markup |
| Also opens in | VS Code, Sublime Text, any code editor |
How to open a JS file online
- Click Choose file above, or drag your JS file onto the box.
- The right viewer loads automatically and renders your file.
- Read, scroll or page through it. To open a different file, choose Open another file.
100% private — files never leave your browser.
Libraries used to render JS in the browser
This viewer is built entirely with open-source JavaScript that runs in your browser:
Frequently asked questions
What is a .JS file?
A .JS file is a Source code file, identified by the text/plain media type. You can open and read it instantly in the viewer above without installing anything.
What programs open JS files?
On the desktop, JS files typically open in VS Code, Sublime Text, any code editor. Online, this page opens them in any modern browser — nothing to download.
Can I edit a JS file online?
Yes. Open your file, switch to Edit, change the text with built-in find & replace, then click Save. It all runs in your browser — nothing is uploaded.
How do I convert JS to an image?
Use Snapshot to capture the JS preview, optionally add arrows, text or highlights, then download it as a PNG image.
Is it safe to open my JS file here?
Yes. The file is read and rendered entirely by JavaScript inside your own browser. It is never uploaded to a server, so nothing leaves your device.
Do I need to install anything to view a JS file?
No. There is nothing to install and no account to create. Open the page, drop your file, and it displays instantly.
Does it work on my phone or iPad?
Yes. The viewer is fully responsive and works in modern mobile and tablet browsers such as Safari and Chrome.
Is there a file size limit?
There is no hard limit, but very large files depend on your device’s memory. Big files are processed in the background so the page stays responsive.