RegExr
Regular expressions can be learned, built, and tested with RegExr, an online editor with reference material.
About RegExr
RegExr is an online editor for learning, building and testing regular expressions. It supports the JavaScript and PHP/PCRE flavors, updates results in real time as you type, and shows details when you roll over a match or the expression itself. A sidebar provides a cheatsheet, a full reference and help, and a Tools area can replace and list output, detail capture groups and describe an expression in plain English.
Patterns can be validated with test suites, and expressions can be saved, shared, forked, favorited and searched or rated among community patterns. Signing in is required to persist favorites and patterns, unsaved changes are lost, and sharing creates a public copy of the expression, including its test text, that cannot be edited or deleted afterward. The site is ad-supported and asks that ad-blockers be disabled for its domain.
Key features
- Real-time match results that update as you type
- JavaScript and PHP/PCRE regular expression flavors
- Tests mode for suites a pattern should or should not match
- Sidebar cheatsheet, full reference and help
- Tools for replace, list output, capture groups and plain-English explanation
- Save, share, fork, favorite and rate community patterns
Best for: Developers and learners who want to write and check regular expressions in a browser without installing a local tool.
Good for
- Covers two regex flavors, JavaScript and PHP/PCRE
- Matches update in real time and hover reveals match or expression details
- Test suites allow validating a pattern before use
Watch out for
- Favorites and saved patterns persist only for signed-in users
- Unsaved changes are lost
- A shared expression becomes a public copy, including its text, that cannot be edited or deleted
RegExr at a glance
- Website
- regexr.com
- Category
- Development › Developer Tools
- Type
- Online tool
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
Guides for Developer Tools
RegExr alternatives
Tools and sites you could use instead, ranked by how closely they match.
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Search directories recursively for regular expression matches with ripgrep, while respecting gitignore rules.
Open source
24 alternativesRegExr comparisons
Featured in
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RegExr FAQ
Do I need an account to use RegExr?
Signing in is needed to persist favorites and patterns; without it, unsaved changes will be lost.
Which regular expression flavors does RegExr support?
JavaScript and PHP/PCRE.
Can I edit or delete an expression after sharing it?
No. Sharing creates a public copy of the expression, including its text, and that shared copy cannot be edited or deleted.
Is something wrong or out of date?
Tell us and an editor will check it.
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