RegexRegex

Free plan Web

What RegexRegex is

RegexRegex is a free browser-based tool for building and testing regular expressions. Its JavaScript checker runs locally and shows matches, captures, pattern explanations, and errors, while also previewing replacements. A guided builder creates basic JavaScript patterns from controls for character types, quantities, groups, boundaries, and flags; it can test the patterns it generates. The builder does not cover every regex syntax feature or turn any arbitrary pattern into an equivalent visual layout. Python, PHP, Java, .NET, and Perl runtimes are available through an online execution service after the user explicitly presses Run. Replacement previews recognize numbered and named capture references such as $1 and $<name>. The searchable reference covers 25 syntax and flag items. Users can save up to 50 test cases in the browser, with each input limited to 20,000 characters. Share links place the selected pattern, engine, flags, and operation in the URL fragment; test and replacement text are excluded unless opted in. A cached JavaScript checker may work offline, but other engine checks require the online service.

Who it suits

RegexRegex suits people who want to test JavaScript expressions in a browser or compose basic patterns with guided controls. It also offers optional online checks for several other regex engines.

What it does well

JavaScript checks run locally in the browser.
Previews replacements with numbered and named captures.
Saves up to 50 test cases in the browser.
Share links omit test text unless users opt in.
A cached JavaScript checker may work offline.

What to know first

The builder covers only basic patterns, not every syntax feature.
Non-JavaScript engines require an online run.
Each test input is limited to 20,000 characters.

Limits

The free plan is listed as free. It allows up to 50 saved browser test cases, each with input no longer than 20,000 characters. The builder covers basic JavaScript patterns rather than every syntax feature; Python, PHP, Java, .NET, and Perl checks require the online execution service.

Plans

Plan	Billed and limits	Price
Free online regex tester	JavaScript checks run in the browser · Python, PHP, Java, .NET, and Perl checks require an explicit online run	Free

As regexregex.com lists them, read 5 Oct 2026. The maker's own page has the final word.

Getting started

Open the RegexRegex website in a browser.
Use the checker to enter a pattern and choose its operation and flags.
Use the guided controls to compose a basic JavaScript pattern, if needed.
Run JavaScript checks in the browser, or press Run for an available Python, PHP, Java, .NET, or Perl engine.
Save test cases in the browser or create a share link with the selected pattern, engine, flags, and operation.

Verdict

RegexRegex offers local JavaScript testing alongside guided pattern building, saved test cases, and replacement previews. Checks using other listed engines require an explicit online run, and the builder is not a full visual representation of every regex.

Questions

How much does RegexRegex cost?

The Free online regex tester plan is listed as free.

Which platforms and regex engines does it support?

It is available on the web. JavaScript runs locally; Python, PHP, Java, .NET, and Perl are available through an online run.

Can it work offline?

A cached JavaScript checker may work offline. The other listed engine checks need the online execution service.

What can the builder do?

It creates basic JavaScript patterns using guided controls for character types, quantities, groups, boundaries, and flags. It does not cover every regex syntax feature.

What does a share link include?

It stores the selected pattern, engine, flags, and operation in the URL fragment. Test and replacement text are excluded unless the user opts in.

Facts from RegexRegex's own pages

Analytics: Cloudflare Web Analytics may collect page and device information, and Google Analytics 4 may use analytics cookies if enabled. · regexregex.com, 5 Oct 2026
Builder: A guided builder creates basic JavaScript RegExp patterns from controls for character types, quantities, groups, boundaries, and flags. · regexregex.com, 5 Oct 2026
Cheat sheet: The checker includes a searchable cheat sheet with 25 regex syntax and flag items. · regexregex.com, 4 Oct 2026
Data handling: The execution service does not record or persist input submitted for optional native engine runs. · regexregex.com, 5 Oct 2026
Engines: JavaScript runs locally; optional Python, PHP, Java, .NET, and Perl runtimes can be used after explicitly pressing Run. · regexregex.com, 5 Oct 2026
Free access: The maker describes the online regex tester as free. · regexregex.com, 4 Oct 2026
Integrations: The opened maker pages describe no external integrations. · regexregex.com, 4 Oct 2026
Language snippets: Python and PHP reference snippets are provided, but only JavaScript RegExp executes unless a native engine is explicitly run. · regexregex.com, 5 Oct 2026
Limits: The maker says patterns are practical starting points and do not guarantee complete validation for every application. · regexregex.com, 5 Oct 2026
Local test cases: Saved test cases stay in the browser, with a maximum input length of 20,000 characters and up to 50 cases. · regexregex.com, 5 Oct 2026
Offline: A cached JavaScript checker may work offline, while Python, PHP, Java, .NET, and Perl checks require the online execution service. · regexregex.com, 5 Oct 2026
Offline use: A cached JavaScript checker may work offline, while native engine checks require the online execution service. · regexregex.com, 4 Oct 2026
Privacy: The privacy policy says the native execution service does not record or persist input submitted for native runs. · regexregex.com, 4 Oct 2026
Purpose: RegexRegex is a browser based tool for testing JavaScript regular expressions and inspecting matches, captures, replacement previews, and errors. · regexregex.com, 5 Oct 2026
Regex builder: The builder lets users compose basic JavaScript patterns from guided controls and inspect and test the generated pattern. · regexregex.com, 4 Oct 2026
Regex features: The checker supports testing matches and captures, previewing replacements, and viewing pattern explanations and errors. · regexregex.com, 5 Oct 2026
Replacement: The tester previews replacements and supports numbered and named capture references such as $1 and $<name>. · regexregex.com, 4 Oct 2026
Share links: Share links restore selected fields; test and replacement text are excluded unless the user explicitly opts to include them. · regexregex.com, 5 Oct 2026
Support: Questions and corrections can be sent to [email protected]. · regexregex.com, 5 Oct 2026
Supported engines: The checker supports JavaScript locally and offers Python, PHP, Java, .NET, and Perl runtimes when available after the user explicitly presses Run. · regexregex.com, 4 Oct 2026

Where RegexRegex stands on Freedom251

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