Invisible regex behavior
Regex Tester highlights every matched span so greedy quantifiers, anchors, and escaped characters become easier to verify.
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Regex Tester Highlight Matches and Capture Groups
Regex Tester lets you test patterns with live highlights, flags, capture groups, match counts, positions, and common templates locally in your browser.
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Regex Tester Problems Developers Avoid
Regex Tester makes regular expressions visible before they reach code, logs, validation rules, or production data.
Missing capture details
Regex Tester lists capture groups beside each match, making it easier to debug parsers, validators, and extraction scripts.
Unsafe paste workflows
Regex Tester runs in the browser, so private logs, emails, API responses, and test strings do not need to leave your device.
Regex Tester Features for Daily Debugging
Regex Tester combines live highlighting, flags, capture groups, positions, match counts, and templates in one focused tool.
Live match highlighting
Regex Tester updates highlighted spans as soon as the pattern, flags, or test text changes.
Flag controls
Toggle global, case insensitive, multiline, and dotAll flags without rewriting the regex literal.
Capture group inspector
See numbered and named capture groups for each match, including positions when the browser supports match indices.
Match count and positions
Review total matches, full match text, and start-end offsets for quick parser debugging.
Common templates
Load email, URL, phone, date, and IP address regex templates with sample text in one click.
Private local processing
Regex Tester uses the JavaScript RegExp engine in your browser and does not upload pasted text.
How to Use Regex Tester
Regex Tester is built for the short debug loop developers use all day: paste, toggle, inspect, and refine.
01
Enter your regex
Paste only the pattern body, then use the flag toggles to control global, case insensitive, multiline, or dotAll matching.
- Paste only the pattern body, then use the flag toggles to control global, case insensitive, multiline, or dotAll matching.
02
Paste test text
Add logs, validation examples, sample input, or copied content. Regex Tester highlights matches immediately.
- Add logs, validation examples, sample input, or copied content. Regex Tester highlights matches immediately.
03
Inspect matches and groups
Review the count, start-end positions, full match text, and capture groups before copying the final pattern.
- Review the count, start-end positions, full match text, and capture groups before copying the final pattern.
Regex Tester Workflows
Use Regex Tester for validation, extraction, and quick pattern reuse without switching tools.
Highlight live matches
Watch Regex Tester mark every match in sample text while you refine anchors, quantifiers, and character classes.
Debug capture groups
Inspect each Regex Tester match with numbered groups, named groups, and start-end positions.
Start from templates
Use Regex Tester templates for email, URL, phone, date, and IP address patterns, then adapt them to your project.
Regex Tester Use Cases
Regex Tester supports common developer workflows where pattern correctness matters.
Form validation
Test email, URL, phone, date, and ID validators before wiring them into a frontend form.
Log parsing
Extract IDs, timestamps, paths, and error messages from copied logs with visible match positions.
Content cleanup
Find repeated patterns, unusual separators, and structured snippets before writing replacement code.
Regex Tester FAQ
Common questions about flags, capture groups, matching behavior, and privacy.
What does Regex Tester show?
Regex Tester highlights matches, counts them, shows start-end positions, and lists capture groups for each match.
Does Regex Tester upload my text?
No. Regex Tester runs with the browser JavaScript RegExp engine, so pasted text is processed locally.
Which flags are supported?
Regex Tester supports global, case insensitive, multiline, and dotAll flags through simple toggles.
Can Regex Tester show capture groups?
Yes. Regex Tester lists numbered and named capture groups for every match, with positions when supported by the browser.
Start Using Regex Tester
Open Regex Tester, paste a pattern and sample text, choose flags, then inspect highlighted matches, capture groups, counts, and positions.
Free forever - browser-only regex tool.