Regex Tester

JavaScript mode uses your browser's own regular expressions. Java, PHP and Python modes accept each language's syntax and translate it so the browser can run it. Most patterns give the same results, and anything that can't be reproduced is reported. Go, .NET and others aren't added yet.

In PHP mode, type the pattern with its delimiters and modifiers, like /\d+/i. In Python mode, use the flag boxes and (?P<name>...) for named groups. Both can read patterns pasted from code, and both give you a ready-made snippet to copy.

Switch to Java, paste the text from between the quotes, and tick "Pattern is a Java string literal" so the doubled backslashes (\\d) become real ones (\d). Then use Copy as Java to get a Pattern.compile snippet back.

g finds all matches instead of the first, i ignores case, m makes ^ and $ match at each line, s lets the dot match line breaks, and u turns on full Unicode support.

Some patterns, such as nested repeats like (a+)+, can take exponentially long on certain text. The tester stops after two seconds so your browser never freezes. Make the pattern more specific to fix it.

No. Matching runs in your browser, in a background worker, and nothing is uploaded.