Regex Tester is a free online tool that tests regular expressions against any input text and displays all matches, their positions, and capture groups. Supports standard JavaScript regex flags including g, i, and m.
A regular expression (regex) is a sequence of characters that defines a search pattern. Regex is used in programming for string matching, validation, and text manipulation. Testing regex patterns interactively helps developers build and debug expressions before using them in code.
Regex Tester
Test regular expressions against text and see all matches instantly in your browser.
How to Use
- Enter your regular expression pattern in the Pattern field
- Set flags (e.g. g for global, i for case-insensitive)
- Paste your test string into the Test String field
- Click Test Regex to see all matches, their indexes, and capture groups
Example
Input
Pattern: \d+ | Flags: g | Text: abc 123 def 456
Output
2 matches found: "123" at index 4, "456" at index 12
FAQ
- What regex flavour does this tool use?
- This tool uses JavaScript's built-in RegExp engine, which follows the ECMAScript regex standard.
- Does this tool support capture groups?
- Yes, capture groups are displayed in the Groups column of the results table.
- Is this tool free?
- Yes, it is completely free with no registration required. All matching runs in your browser.