Regex Tester

Online tool for testing regular expressions on text with flags, groups, and match highlighting.

Обработка выполняется локально в браузере. Данные не отправляются на сервер.

For this tool, processing runs locally in your browser and data is not sent to the server.

Regex Tester is a free online tool for testing regular expressions on text in the browser with JavaScript RegExp. Processing runs locally in your browser.

What it does

Output

Processing

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How to use

Enter a regular expression without outer slashes or paste /pattern/flags format.
Choose flags: global, ignore case, multiline, dotAll, unicode, or sticky.
Paste text to test and click Test.
Review match count, highlighting, positions, capture groups, and named groups.

More about this tool

Regex Tester helps test regular expressions on text directly in the browser.

Supports JavaScript RegExp, flags g, i, m, s, u, and y, shows matches, start/end positions, capture groups, and named groups.

Useful for debugging filters, form validation, log search, email, URL, date, ID, and text pattern checks. Limits on text length and match count protect the browser.

Processing runs locally in your browser.

Tests JavaScript regex
Supports flags g, i, m, s, u, y
Shows matches and positions
Shows capture groups and named groups
Highlights matches in text
Uses limits to prevent browser hangs
Runs in the browser
Data is not sent to the server
No registration required

Frequently Asked Questions

How do I test a regular expression?

Enter the pattern, choose flags, paste test text, and click "Test". The tool shows matches, positions, and groups.

Do I need slashes around the regex?

You can enter only the pattern without outer slashes, e.g. \d+. If you paste /\d+/gi format, the tool may detect pattern and flags automatically.

What does the g flag mean?

Flag g enables finding all matches. Without it JavaScript RegExp usually returns only the first match.

What does the i flag mean?

Flag i enables case-insensitive matching, so Text, text, and TEXT count as matches.

What does the m flag mean?

Flag m changes ^ and $ behavior so they work for individual lines, not only the whole text.

Does the tool show capture groups?

Yes. It shows regular capture groups and named groups when present in the regex.

Why can regex hang on large text?

Some patterns with nested quantifiers can run very long. The tool uses limits on text length and match count.

Is this PCRE or JavaScript regex?

The tool uses JavaScript RegExp in the browser. Syntax may differ from PCRE, Python, PHP, .NET, and other engines.

Can I replace text with regex here?

This service tests regular expressions. For text replacement use a dedicated regex replace or find-and-replace tool.

Is my data sent to the server?

No. Processing runs locally in your browser and data is not sent to the server.

Do I need to register?

No. The tool works without registration.

More about this tool

Regex Tester helps test regular expressions on text directly in the browser.

Supports JavaScript RegExp, flags g, i, m, s, u, and y, shows matches, start/end positions, capture groups, and named groups.

Useful for debugging filters, form validation, log search, email, URL, date, ID, and text pattern checks. Limits on text length and match count protect the browser.

Processing runs locally in your browser.

Tests JavaScript regex
Supports flags g, i, m, s, u, y
Shows matches and positions
Shows capture groups and named groups
Highlights matches in text
Uses limits to prevent browser hangs
Runs in the browser
Data is not sent to the server
No registration required

Frequently Asked Questions

How do I test a regular expression?

Enter the pattern, choose flags, paste test text, and click "Test". The tool shows matches, positions, and groups.

Do I need slashes around the regex?

You can enter only the pattern without outer slashes, e.g. \d+. If you paste /\d+/gi format, the tool may detect pattern and flags automatically.

What does the g flag mean?

Flag g enables finding all matches. Without it JavaScript RegExp usually returns only the first match.

What does the i flag mean?

Flag i enables case-insensitive matching, so Text, text, and TEXT count as matches.

What does the m flag mean?

Flag m changes ^ and $ behavior so they work for individual lines, not only the whole text.

Does the tool show capture groups?

Yes. It shows regular capture groups and named groups when present in the regex.

Why can regex hang on large text?

Some patterns with nested quantifiers can run very long. The tool uses limits on text length and match count.

Is this PCRE or JavaScript regex?

The tool uses JavaScript RegExp in the browser. Syntax may differ from PCRE, Python, PHP, .NET, and other engines.

Can I replace text with regex here?

This service tests regular expressions. For text replacement use a dedicated regex replace or find-and-replace tool.

Is my data sent to the server?

No. Processing runs locally in your browser and data is not sent to the server.

Do I need to register?

No. The tool works without registration.