What this Regex Tester does

This Regex Tester helps you test regular expression patterns against sample text. It is useful for checking pattern matching, validating text formats, extracting numbers or words, and debugging JavaScript regular expressions.

Regular expressions are commonly used in programming, data cleaning, search tools, form validation, log analysis, and text processing.

How to use this tool

1. Enter a regular expression pattern such as \d+ or [A-Za-z]+.
2. Choose flags such as g for global search or i for case-insensitive search.
3. Paste sample text into the text box.
4. Click Test regex.
5. Review the match count, matched values, and highlighted text.

Common regex flags

• g — global search; finds all matches instead of stopping at the first match.
• i — case-insensitive search.
• m — multiline mode.
• u — Unicode mode.

Important privacy note

This MVP version is designed to test regex patterns locally in your browser. Do not paste passwords, API keys, private tokens, credentials, logs with secrets, customer data, or confidential business text into any online tool unless you understand how that tool handles data.

FAQ

What is a regular expression?

A regular expression, or regex, is a pattern used to match parts of text. Regex can find numbers, words, email-like patterns, dates, codes, and other text structures.

Why does \d+ match numbers?

In JavaScript regular expressions, \d matches a digit and + means one or more times. So \d+ matches one or more digits.

Why do I need the g flag?

The g flag tells the regex engine to find all matches. Without it, JavaScript usually returns only the first match.

Does this tester use JavaScript regex?

Yes. This tool uses the browser’s JavaScript regular expression engine, so behavior should match standard JavaScript regex behavior.

Related tools

You may also want to use the JSON Formatter for data formatting, the Statistics Calculator for numerical summaries, or the Prompt Optimizer for AI workflow tasks.