Frequently Asked Questions
Regex Tool FAQ
How do I test a regular expression?
Enter your pattern and flags, add test text, and click Run Test to inspect matches and indexes.
What flags are supported?
This uses JavaScript regular expressions and supports flags like g, i, m, s, u, and y.
Can I test regex without uploading data?
Yes. Input text is processed locally and is not sent to a backend service.
Example input/output
Input: Pattern: \d+ / Input: Order 123 and item 456
Output: Matches: 123, 456
How it works
This tool constructs a JavaScript RegExp from your pattern and flags, then runs exec() in a loop to collect all matches and their positions. Match positions are highlighted in the input. Processing runs in your browser.
Common use cases
- Test regular expressions against sample input during development
- Debug regex patterns that produce unexpected matches
- Quickly validate a regex before adding it to source code