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Regex Tester & Matcher online, free
Test JavaScript regular expressions against target text, visualize match groups, extract capture offsets, and validate syntax.
- Runs in your browser — no upload
- Free, no sign-up, no watermark
- TXT
How to use Regex Tester & Matcher · Regex Tester & Matcher — frequently asked questions
How to use Regex Tester & Matcher
- 1
Add your TXT file
Drop a file on the page, paste it, or click Select Files. Nothing is uploaded — it opens straight in your browser.
- 2
Fine-tune the settings
The defaults already suit most files; change them only if you need to.
- 3
Run Regex Tester & Matcher
Press the start button. Processing happens on your device, usually in seconds.
- 4
Download the result
Save the finished file, or continue with another tool without downloading in between.
What Regex Tester & Matcher can do
- Private by design — files are processed in your browser and never uploaded
- Free with no sign-up, no watermark and no daily limit
Regex Tester & Matcher — frequently asked questions
Which regex engine does the tester use?
The tester utilizes the JavaScript ECMAScript regular expression engine built directly into your web browser, providing instantaneous matching with zero server latency.
Which regex flags are supported?
It supports all standard RegExp flags including `g` (global search), `i` (case-insensitive), `m` (multiline mode), `s` (dotAll mode), `u` (unicode), and `y` (sticky).
Does the tool highlight matched capture groups?
Yes. Each match is detailed with its overall matched string, start and end index offsets, and all named and numbered capture groups.
How does it handle syntax errors or invalid regular expressions?
Syntax errors (such as unclosed parenthesis or invalid character classes) are trapped gracefully with clear error descriptions indicating the syntax fault.
Are my test strings and regex patterns kept private?
Yes. All regex execution, testing, and group extraction happen strictly inside your client browser environment. No text or regex queries are sent to external servers.
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