Helpful information

See where a regular expression matches the input, how capture groups are divided, and what the result looks like after applying a replacement.

Input never leaves your device. Processing uses your local computer only.

Matching and replacement happen entirely in your current browser. Nothing is sent to the MISCLAND server.

Q. What do the flags mean?

g finds all matches, i ignores letter case, m enables multiline mode, s lets dots match line breaks, and u enables Unicode mode.

Q. What does $1 mean in a replacement?

It refers to a capture group. For example, the first group captured by (\\d+) can be reused as $1.

Q. What should I do if the regular expression is invalid?

Check parentheses, brackets, and escaped backslashes. The error message appears in the status area.

Q. Can it handle large text?

Processing happens in your browser, so very large input or complex expressions may be slow.

Extract email addresses: Quickly find email addresses in logs or documents.

Clean up text: Send replacement output to the Bulk Text / CSV Cleaner for further cleanup.

Development: Useful for validating URL, UUID, date, and phone number patterns.

Debugging: Inspect capture groups to reduce errors in API and log parsers.

It uses the browser's JavaScript RegExp (ECMAScript) engine. PCRE, Python, Java, and .NET can differ in syntax and behavior, so verify the pattern again in your target runtime.

Yes. You can check not only the pattern matching location and capture group, but also the results of applying the replacement string. Verify patterns and substitution results with sample text before putting them into actual code.

Regex Tester Online (Test & Replace Regular Expressions)

Common patterns

Helpful information

What does the Regex Tester show?

Where is the input text processed?

Frequently asked questions (FAQ)

Tips

Which regex engine does this tester use?

Can I check regular expression tests and substitutions in Regex Tester?