Regex Generator
Build regular expressions from examples, with ready-made patterns for common cases.
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How to use it
- Choose a ready-made pattern (email, URL, IPv4, date, slug and more) or switch to the sample-based mode.
- In sample mode, type an example string and the tool derives a character-class pattern from it.
- Read the explanation to understand what each part of the pattern matches — and its known limitations.
- Use "Open in Regex Tester" to validate the generated pattern against your own data immediately.
About this tool
Pick a common target — email, date, IP address, URL and more — or describe matching rules from sample strings, then get a starting pattern with an explanation of each part. The result opens directly in the Regex Tester for immediate validation against your own data.
Your input never leaves the browser: this tool works entirely offline once the page has loaded.
Frequently asked questions
Can the sample mode produce a perfect regex?
No tool can guarantee that. The sample mode derives character-class patterns from your example — a starting point to refine in the Regex Tester with real data.
Why does the IPv4 pattern accept 999.999.999.999?
It checks structure (four dot-separated digit groups), not the 0–255 range. The pattern's explanation documents this limitation; strict validation needs extra logic in code.