Test regex
Write a regular expression and a text to try it on. The engine is the browser’s own, the same one your code will use: what you see here is what you will get.
Your text stays on your device: nothing is uploaded
Result
Paste something on the left: the result appears as you type.
How it works
Every language has its own regular expression engine, and the differences between them are why a regex “tested online” sometimes does not work in your code. There is no engine of ours here: we use the browser’s, which is the same one any JavaScript uses. We show every match with its position, its line and its captured groups, named ones included. One warning worth more than any feature: some expressions take exponential time on badly shaped input — (a+)+b on a row of “a” never finishes, and in JavaScript there is no way to interrupt it. That is how you accidentally write the regex that takes a server down, and if you are reading this page you may have just done it. There are only two possible defences, and both are here: a cap on the text length and one on the number of matches.
What you paste is never uploaded. Anywhere.
Not to a server of ours, not to a third party, never. The text you type stays in your browser’s memory: it is read, processed and shown here, and you copy it. There is no path that takes it elsewhere, because there is no server to send it to. You can paste something confidential.
- Processed locallyThe computation happens on this page, using the browser’s own engine: no request goes out while you type.
- Nothing to upload, nothing to wait forOther services send your file to a server and then send it back to you. Here the file never leaves: there is no upload to wait for.
- No accountNo sign-up, no email, no daily limits to get around by paying.
- Nothing to deleteOthers promise to delete what you paste after an hour. We have nothing to delete: it never reached us.