Write a regular expression and watch it match your text live. Matches are highlighted, capture groups are listed, and a replace preview shows exactly what a substitution would produce. Ideal for validating input, scraping and search-and-replace work.
A UUID identifies a record — never use it as an authentication token.
Math.random() is predictable. Use the CSPRNG for tokens, IDs and secrets.
Decoding is not verifying. Always validate the signature and claims on the server.
Generate keys here, then store them in environment variables or a vault.
Write a regular expression and watch it match your text live. Matches are highlighted, capture groups are listed, and a replace preview shows exactly what a substitution would produce. Ideal for validating input, scraping and search-and-replace work.
Type your regular expression between the slashes, then toggle the flags you need.
Every match is highlighted instantly, and numbered groups are listed below.
Enter a replacement (with $1, $2…) to see the transformed text without changing your input.
| Pattern | Matches |
|---|---|
| \d+ | One or more digits |
| \w+@\w+\.\w+ | Simple email address |
| ^https?:// | URL at the start |
Start simple and add groups only when you need to extract parts.
It is completely free, private and requires no signup.
Use the tool nowA pattern that describes a set of strings, used to search, validate and replace text. It is supported by virtually every programming language.
g finds all matches, i ignores case, m makes ^ and $ match line boundaries, s lets . match newlines, and u enables full Unicode.
No. Matching runs entirely in your browser using the native JavaScript RegExp engine.
Explore the whole collection — no signup, 100% free & private.