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Regular expression tester
Evaluate a regular expression against text, adjust its flags, and inspect the matches to refine your pattern more easily.
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- Instant
- Free
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- Works offline
- Clipboard
Pattern
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Matches
Why use this tool?
Test a regular expression against text and inspect matches immediately before using the pattern in code or validation logic. It is useful for building a regex step by step, checking capture groups, or understanding why a pattern does not match the text you expect.
Smart processing
Generate, convert, or validate technical data with purpose-built controls.
Supported formats
Technical formats and syntaxes suited to each generator, converter, or validator.
Save time
Get a clean, ready-to-use result in seconds without installing software or configuring a complex workflow.
Guide
How to use this tool
- 1
Paste the test text
Add a representative example of the content your regular expression needs to handle.
- 2
Enter the regex and flags
Provide the pattern and enable useful options such as case-insensitive or global matching.
- 3
Inspect the matches
Review the results and refine the pattern until it matches your intended cases accurately.
Tips and best practices
- Start with a simple pattern and add groups, quantifiers, and alternatives gradually to make debugging easier.
- Test several examples, including cases that should not match, before using a regex for validation.
- Very complex regular expressions can become hard to maintain, so prefer readable patterns when several approaches are possible.
Frequently asked questions
What is a regular expression used for?
A regex can search, extract, or validate text by describing a pattern.
What do regex flags change?
They alter matching behavior, for example by ignoring case, finding multiple matches, or handling multiline text differently.
Why does my regex fail to match expected text?
The pattern may be too strict, some characters may need escaping, or a required flag may be missing for the tested case.
Are the text and regex uploaded to a server?
No. Evaluation runs locally in your browser.
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