JavaScript Tester
Use this free online JavaScript Tester to run JavaScript code online and see console output. It works instantly in your browser, and your data never leaves your device.
About the JavaScript Tester
Write or paste JavaScript and run it right in your browser. console.log output and errors are captured and shown below, which is perfect for quick experiments.
Also known as: run javascript online, js console online, js compiler.
How to use the JavaScript Tester
- Paste your input into the box above, upload a file, or click Sample to try an example.
- Pick any options you need. The JavaScript Tester processes your input instantly as you type.
- Click Copy to copy the output or Download to save it as a file.
Features
- Free with no signup and no daily limits
- Private: runs entirely in your browser
- Works on mobile, tablet and desktop
- Upload files and download results
- Live results as you type, with clear error messages
- Clean, fast interface with no popups
Frequently asked questions
Is the JavaScript Tester free to use?
Yes. The JavaScript Tester is completely free with no signup, no limits on normal use and no watermark.
Is my data safe?
Yes. Everything is processed by JavaScript inside your own browser. Your text is never uploaded to our server or stored anywhere.
Can I choose the indentation?
Yes. Pick 2 spaces, 4 spaces or tabs from the options, and the output updates instantly.
Does it work offline and on mobile?
Once the page has loaded, the tool runs in your browser and works on phones, tablets and desktops.
What else is this tool called?
People also search for it as run javascript online, js console online, js compiler. It is the same free tool.