Test a regular expression against your text and see all matches and groups - locally in your browser, with no upload.
Running locally on your device ...
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Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
A regular expression (regex) describes a search pattern for text - such as "all email addresses", "any number" or "words starting with A". They are powerful but tricky: a small mistake in the pattern leads to quite different matches. This tool lets you run a pattern against a test text and immediately shows all matches with their position and the captured groups, so you can try out and refine the pattern safely.
You enter the pattern and can set the common switches: ignore case (i), multiline (m, makes start and end apply per line), dot matches newline (s), Unicode (u, correct handling of surrogate pairs and \p{} classes like \p{L}) and match only at the current position (y, the so-called sticky mode - the match must start exactly at the last position). The tool always searches globally, that is for all matches, and outputs the result as clear JSON: the number of matches plus, for each match, the found text, its position and the contents of the capture groups.
The whole evaluation runs entirely locally in your browser in pure JavaScript with the built-in regex engine - your test text is not uploaded, not stored, and no foreign library is loaded from a CDN. If the pattern is invalid, the tool says so honestly instead of inventing a wrong result.
| Input formats | Text input |
|---|---|
| Output format | JSON |
| Batch processing | No |
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: It uses JavaScript regex syntax (ECMAScript); other dialects (PCRE, Python) may differ in details. The search is always global. Very long texts are limited, and an extremely unfavorable pattern can be slow - the tool caps the work instead of blocking the browser. An invalid pattern leads to an honest error.
No. The evaluation runs entirely locally in your browser; your test text and the pattern never leave your device and are not stored.
The JavaScript (ECMAScript) syntax of the built-in engine. Patterns from other languages like PCRE or Python usually work but can differ in details.
i ignores case, m makes line start and end apply per line, s lets the dot also match line breaks, u enables Unicode mode (needed for \p{} classes and correct surrogate pairs), y (sticky) only allows a match exactly at the current position. Global (all matches) is always active.
The tool reports an honest error instead of producing a wrong result. Check the brackets and escapes in the pattern.