What is Regex Checker?

Regex Checker is a tool for testing JavaScript regex patterns against text and reviewing where they match. It fits work like drafting validation patterns for email or URL input and building extraction rules, when you want to quickly verify behavior before using a pattern in code.

Changing the pattern, text, or flags updates the result right away. Non-matching input and invalid patterns can be tried as they are.

How to Use

1. Enter the regex pattern you want to test.
2. Paste the target text into the text area.
3. Turn the g, i, and m flags on or off as needed.
4. Review the match result and highlighted sections, then adjust the pattern.

A short one-line sample is enough for quick checks, but multi-line text is helpful when you want to confirm how line-based conditions behave.

Main Settings

Find all matches g

Turn on the g flag to find every match instead of stopping at the first one. It fits extraction patterns and repeated values.

Ignore letter case i

Use the i flag to ignore uppercase and lowercase differences. It helps when you want to accept variations in user input.

Treat input as multi-line text m

Turn on the m flag to make ^ and $ work with each line instead of only the start and end of the full string. Try it with multi-line text to see how line anchors behave.

Use Cases

• Drafting validation patterns for forms and input checks
• Testing extraction rules for URLs, email addresses, or numeric strings
• Checking whether a log or document contains values in a specific format

Things to Keep in Mind

• This tool assumes JavaScript regex syntax, so some features may behave differently from other languages.
• The input field is meant for the pattern itself rather than a full regex literal in source code. When you move a tested pattern into code, adjust escaping to match the string syntax of the language you use.