Regex tester
Tool processing runs in your browser — your pastes/files are not uploaded to our servers for processing. Ads (if shown) load separately and do not receive your tool inputs.Advertising · Details
Quick answer
Enter a pattern and flags, paste a test string, see matches instantly. Copy as JavaScript or Python — browser RegExp only. Share a recipe with ?recipe=email (preset only — never puts your test string in the URL).
Embed this tool
Paste this iframe on your site. Includes a backlink to Regex Tester. Opens chrome-less with ?embed=1.
Testing for Java, C#, Python, or PCRE
This tester runs your pattern through the browser's own JavaScript engine, so what you see is precisely JavaScript regex behaviour. Most everyday patterns — character classes, quantifiers, anchors, alternation, capture groups — behave identically across languages, so a pattern you get working here will usually port unchanged. The differences worth knowing before you paste it elsewhere:
- Named groups. JavaScript and .NET write
(?<name>...); Python uses(?P<name>...). The reference syntax differs too. - Escaping in source code. Java and C# strings need the backslash doubled unless you use a verbatim or text-block literal, so
\dbecomes\\d. This is the single most common reason a pattern that worked here fails once pasted into code. - Lookbehind. Supported in modern JavaScript, .NET, and PCRE. Python's built-in
rerequires it to be fixed-width. - Unicode.
\p{...}property escapes need theuflag in JavaScript; other engines enable them by default or not at all.
Where behaviour is likely to diverge, confirm the final pattern in the language you are shipping — a tester in one flavour cannot promise another engine's edge cases.
Frequently asked questions
How do I test a regular expression?
Enter a pattern and flags (for example g or gi), paste a test string, and matches appear instantly. Use a recipe button to load a common pattern with sample text.
Can I copy the regex as code?
Yes. Copy as JS produces a JavaScript RegExp literal; Copy as Python produces a re.compile-style snippet you can paste into a script.
Which regex flavor is this?
It uses the browser’s native JavaScript RegExp engine — the same rules as in Chrome, Firefox, and other modern browsers.
Is my input uploaded?
No. TryDevSnip runs RegExp entirely in your browser. Nothing you paste is uploaded to our servers for processing.