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RegexRegex

regexregex.com

Free plan Web
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Spec score 7.9 #8 of 23 in Regular Expression Testers

What it is

RegexRegex is a free browser-based tool for building and testing regular expressions. Its checker runs JavaScript patterns in the browser and shows matches, captures, explanations, and errors, with previews for replacement text. A guided builder composes basic JavaScript patterns using controls for character types, quantities, groups, boundaries, and flags. It can test the pattern it creates, but does not cover every syntax feature or convert arbitrary patterns into an equivalent visual layout. Python, PHP, Java, .NET, and Perl engines can be used by explicitly pressing Run, which sends checks to an online execution service. Replacement previews recognize numbered and named captures such as $1 and $. The searchable reference covers 25 syntax and flag items. Users can save up to 50 test cases in the browser, each with input up to 20,000 characters. Share links include the selected pattern, engine, flags, and operation; test and replacement text are omitted unless users opt in. A cached JavaScript checker may work offline, while checks using other engines need the online service.

Spec sheet

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

Plans and prices

Free online regex tester Free JavaScript checks run in the browser · Python, PHP, Java, .NET, and Perl checks require an explicit online run Read 5 Oct 2026 · regexregex.com

Every RegexRegex plan and price →

Strong points and limits

Strong points

  • JavaScript checks run locally in the browser.
  • Replacement previews support numbered and named captures.
  • Users can save up to 50 browser test cases.
  • Test and replacement text are excluded from share links by default.

Limits

  • The guided builder does not cover every regex syntax feature.
  • Non-JavaScript engine checks require the online service.
  • Each test input is limited to 20,000 characters.
  • Offline use may be limited to the cached JavaScript checker.

Who it suits

RegexRegex suits people who need to inspect JavaScript regular expressions in a browser or assemble basic patterns with guided controls. Users needing other listed engines can run them through the online service.

Verdict

RegexRegex combines a local JavaScript checker with a guided builder and optional online runs for other engines. Its saved-case limits and builder scope are explicit constraints for more complex workflows.

Where Specifiction places it

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