Developer Tools
Regex Tester
Test regular expression matches, groups, and replacements in the browser.
Input / output
Browser local
Matches, capture groups, and replacement output are calculated in a browser Worker without server upload.
Matches
2
Rendered
2
Capture groups
2
Input chars
15
Match table
| # | Match | Start | End | Length | Groups |
|---|---|---|---|---|---|
| 123 | 4 | 7 | 3 | 1 | |
| 456 | 12 | 15 | 3 | 1 |
Capture group table
| # | Group | Value |
|---|---|---|
| 1 | group 1 | 123 |
| 2 | group 1 | 456 |
Replacement preview
abc #123 def #456
Safety budget
- Input limit
- 20,000 chars
- Max matches
- 500
- Worker timeout
- 300ms
- Risk precheck
- nested quantifier block
HelpOpen usage notes, examples, practical tips, and FAQ only when you need them.
What is this tool?
Regex Tester is a browser-first tool for test regular expression matches, groups, and replacements in the browser. It fits into the developer workflow and keeps the main task on one page.
How to use it
- Enter the input
Paste or edit the value in the input area. Sample values are safe placeholders for testing the tool.
- Adjust options
Choose the mode, format, unit, or count that matches the regex, regular expression, pattern test task.
- Review the result
Run the tool, inspect the output, then copy or download it only when the result matches your expectation.
Examples
Regex Tester example
- Input
- Sample input
- Output
- Review the result in the browser.
Practical tips
- For large inputs, process the smallest useful sample first to keep the browser responsive.
- Ad slots are intentionally kept away from tool controls and result panes.
FAQ
What input should I use with Regex Tester?
Use values that match the regex, regular expression task, then adjust the visible options before running the tool.
Can I copy the Regex Tester result?
Yes. Review the output first, then copy or download it when the result matches your expectation.
Can I use Regex Tester on mobile?
Yes. The input, options, action, and result areas are designed to stack cleanly on small screens.
Will ads interrupt Regex Tester?
No. Ad slots stay outside the input, output, and primary action areas so the tool remains usable and policy-safe.