Add the source content
Paste code or technical input, upload a supported REGEX and plain text file, or load the working example. Check headers, delimiters, syntax, or line structure before processing.
Developer tools
Regex Tester
Result
The result will appear here after you run the tool.
The result will appear here after you run the tool.
The result will appear here after you run the tool.
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About this tool
About this tool
Regex Tester checks a regular expression against sample text by matching patterns, listing captures and groups, and measuring performance in your browser. You can test flags and edge cases without uploading data.
Test regular expressions, inspect matches, capture groups, and replacements. Use the full-width workspace to test content or expressions while reviewing syntax, encodings, protocol fields, and implementation details. The tool accepts REGEX and plain text, provides focused options, and creates MATCHES output that you can inspect, copy, download, or save as a local draft.
Built for daily work
How to use this tool
How to use this tool
Configure the operation
Review Pattern, Flags, and Replacement. The selected controls determine how the Regex Tester interprets the source and builds the result.
Run the tool
Start the Regex Tester and review the result, visual preview, and technical report. Correct any reported issue and run the tool again when necessary.
Export or continue the workflow
Copy or download the MATCHES result, save a browser-local draft, or open a related tool for the next conversion, validation, or cleanup step.
Key features
Key features
Live match highlighting with group capture display
Matches are highlighted in the test string as you type. Named and numbered capture groups are listed separately below the result.
Flag toggles for case, multiline, and dotall
Enable or disable global, case-insensitive, multiline, dotall, and sticky flags to match the behavior of your target runtime.
Replacement preview with backreferences
Enter a replacement string with $1-style backreferences and see the substituted output before copying it.
Match list with index and value
All matches are listed with their position in the test string and the matched text so you can verify boundary behavior.
Practical use cases
Practical use cases
Private by default
For local tools, input is processed in your browser and is not sent to application analytics.
Data processing noticeTechnical details
Technical details
Input formatsREGEX and plain text
Output formatsMATCHES
ProcessingLocal browser processing
Task controlsPattern, Flags, and Replacement
Maximum local file25 MB per supported file
Workspace featuresFocus mode, examples, copy, download, local drafts, and result reports
Limitations and important notes
Limitations and important notes
- Test edge cases and production-sized samples before relying on the result.
- Large or deeply structured input depends on available browser memory and may process more slowly on mobile devices.
- The tool implements practical browser-based processing and may not reproduce every feature of specialist desktop software or every vendor-specific extension.
- Keep the original source and review generated output before production, security-sensitive, financial, legal, or safety-critical use.
Frequently asked questions
Frequently asked questions
It evaluates a regular expression against sample text by showing matches, capture groups, and types directly in your browser, with flag support for global and case insensitive searches.
The tester uses JavaScript RegExp. PCRE-specific features not available in JavaScript will not match.
You can test up to 25 MB of text locally, though complex patterns may become slower with larger data.
It reports match counts and groups to help identify catastrophic backtracking, but review patterns for production use.
Related guides and solutions
Related guides and solutions
How to test regular expressions with reliable examples
A practical regex testing method built around representative positive cases, negative cases, capture groups, replacement previews, and performance review.
Learn moreA safe workflow for cleaning text and line-based data
A step-by-step text cleanup process that uses small reversible changes, diff review, and Unicode awareness instead of destructive one-click normalization.
Learn moreWhat local browser processing means for online tools
A transparent explanation of local tool processing, temporary browser memory, local storage, downloads, analytics boundaries, and cases that require remote services.
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