What is Regex Tester?
A Regular Expression (Regex or RegExp) is a sequence of characters that forms a search pattern used for string matching, text validation, and string replacements.
How to use this tool
- Enter your Regex pattern in the pattern bar.
- Toggle execution flags (-g global, -i case-insensitive, -m multiline).
- Type or paste target test text into the input panel.
- Inspect total matches and capturing group breakdowns in real-time.
Example
Input:
Pattern: ([0-9]{4})-([0-9]{2})-([0-9]{2})Output:
Match: 2026-09-12 (Group 1: 2026, Group 2: 09, Group 3: 12)
Common Use Cases
- Validating email, URL, phone number, or password input formats.
- Extracting specific substrings or IDs from complex server logs.
- Crafting search-and-replace regular expressions for IDE refactoring.
Frequently Asked Questions
What does the -g flag do?
The global (-g) flag causes the regex engine to search for all occurrences in the test text rather than stopping after the first match.