Build a regular expression without memorising the syntax: stack blocks such as digits, letters, exact text, character sets and either/or choices, set how often each repeats, or start from a ready-made preset. The regex, a plain-English description, a live test and code snippets update instantly.
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How to use the Regex Generator
Pick a preset such as Email or Date, or start from scratch with Clear all.
Add blocks from the palette: for example Digits, then Exact text "-", then Digits again.
Set how many times each block repeats (exactly once, optional, one or more, exactly N, N to M) and tick capture to save a part as a group.
Choose options: keep Match whole input on for validation, or turn it off to find matches inside longer text; toggle flags like ignore case.
Test and copy: type sample lines to see which match, then copy the regex or the code for your language.
A regex used to validate a single value (a form field, a file name, an ID) should be anchored with ^ and $, otherwise "abc123xyz" would pass a digits-only check because it contains digits. A regex used to extract values from a longer text must not be anchored to the whole input, and usually needs the g flag so that every occurrence is found. Word boundaries (\b) help to avoid matching inside longer words or numbers.
Regular expressions check the shape of text, not its meaning. A date regex can reject month 13, but checking that February 30 does not exist, that an email inbox is real or that a credit card number passes the Luhn check needs code.
Frequently asked questions
How do I create a regex without knowing the syntax?
Describe the text as a sequence of parts. For a product code like AB-1234 you would add Uppercase (exactly 2), Exact text "-" and Digits (exactly 4). The generator turns that into ^[A-Z]{2}-\d{4}$, escapes special characters for you and shows which of your test lines match.
What does "Match whole input" do?
It wraps the pattern in ^ and $ so the entire value must match, which is what you want for validating form fields. Turn it off to search for the pattern anywhere inside a longer text, for example to extract all prices or hashtags from a paragraph.
Is the email regex fully RFC 5322 compliant?
No regex that people can maintain is. The preset accepts the addresses used in practice (letters, digits, dots, plus, percent, hyphen and underscore before the @, a domain and a TLD of at least two letters) and rejects obvious mistakes. To be sure an address exists, send a confirmation email.
What is the difference between capture and non-capturing groups?
A capturing group saves the matched text so you can read it later (match[1] or match.groups.name in JavaScript). The generator automatically uses non-capturing groups (?:…) when it only needs parentheses to apply a quantifier, so your group numbers stay predictable.
Will the regex work in Python, PHP or Java?
The code tab converts the pattern for each language: Python gets (?P<name>…) groups and re flags, PHP gets delimiters and escaped quotes, Java and C# get properly escaped string literals and Ruby uses \A and \z for whole-input matching. Go's RE2 engine does not support lookarounds or backreferences, and the tool warns you when a pattern uses them.
What does lazy mean?
By default quantifiers are greedy and match as much as possible. A lazy quantifier matches as little as possible, which matters when the same character can appear later, for example matching the shortest text between two quotes.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.