TOOL
Regex Difference
Build a regex for 'strings matching pattern A but not pattern B' from two patterns, one per line. Semantics are asymmetric: A must match from the start of the string, while B is rejected if it occurs anywhere. Output shape: (?=A)(?!.*B).*
Try an example:
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Recent history
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How to use
- Type or paste your input into the input box.
- Adjust any parameters if needed.
- Copy or download the result.
Frequently asked questions
- Is my data uploaded anywhere?
- No. All processing happens locally in your browser with no server round-trip.
- Does this tool work offline?
- Yes. Once the page loads, the tool runs entirely client-side and needs no network connection.
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