Regex Tester (Python syntax)
Test a regular expression against your text: see every match, the capture groups and a plain-English breakdown of the pattern. Runs in a sandbox with a timeout.
Forged in Faith, Built to Last
Uses Python's re syntax, which is close to JavaScript, PCRE and Java for everyday patterns (lookbehind and named-group syntax differ slightly).
Free vs Pro
Free
- Highlighted matches and capture groups
- Plain-English explanation of the pattern
- Flags: ignore case, multiline, dotall, verbose
- Safe timeout for runaway patterns
No account needed. Nothing you type is saved. With a free account (no card): 2 full PDF/CSV exports a month, shared across all tools.
Pro adds
- Find-and-replace preview
- Ready-to-paste Python and JavaScript code
- 100 KB test text
- CSV export of matches
- JSON API with your licence key
Get Pro: CA$5.00 CAD/month or CA$49.00 CAD/year · one plan for all our tools · cancel any time · secure Stripe checkout
About this tool
Regex Tester: Test and Explain Regular Expressions is a free online tool from Crusader Empire: Test a regular expression, see every match and group, and get a plain-English breakdown. Free. Paste a regular expression and some text to highlight every match, list capture groups and explain the pattern step by step. Runs in a sandbox with a timeout, so a runaway pattern can't hang it.
Free: Highlighted matches and capture groups, Plain-English explanation of the pattern, Flags: ignore case, multiline, dotall, verbose. Pro adds: Find-and-replace preview, Ready-to-paste Python and JavaScript code, 100 KB test text.
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What would make Regex Tester: Test and Explain Regular Expressions more useful? Bugs, missing features, confusing wording: our R&D team reads every suggestion. Nothing is offered in return, and we never publish reviews without permission.