Regex Tester
The Regex Tester lets you write a regular expression and see matches against your sample text in real time. It highlights captures, named groups and explains why a pattern matches or fails.
Key Features
- Live match highlighting
- Capture and named groups
- Common flags (g, i, m, s)
- Explain mode for pattern breakdown
- Replace preview
- No server involved
Use Cases
- Extract emails or IDs from a log
- Validate an input format
- Build a find-and-replace pattern
- Learn how a tricky pattern behaves
How to Use
- Paste your sample text
- Write the regular expression
- Toggle flags as needed
- Read the highlighted matches and groups
- Use the replace view to preview changes
Practical Tips
- Start simple and add constraints gradually
- Use non-capturing groups (?:...) to reduce noise
- Test edge cases like empty strings and unicode
FAQ
- What does the g flag do?
- It returns all matches instead of stopping at the first.
- Why does my pattern match too much?
- A greedy quantifier may over-match; try a lazy one or a tighter character class.