List Compare Tool - Extract Differences, Intersection, and Union

How to Use

1. Enter the first list in 'List A', one item per line
2. Enter the comparison list in 'List B', one item per line
3. Optionally enable 'Case insensitive' or 'Trim whitespace' options
4. Four results are displayed in real time: Only in A, Only in B, In both, All unique
5. Use the 'Copy' button next to each result to copy it to your clipboard

Usage Examples

Comparing permission lists:
Compare A (old permissions) and B (new permissions) to find added permissions (Only in B) and removed permissions (Only in A)

Checking email list duplicates:
Compare two mailing lists to identify addresses in both (Intersection)

Comparing dependency lists:
Compare the package dependencies from two project package.json files to find differences

FAQ

Is my data sent to a server?

No. All processing happens in your browser.

How are duplicate lines handled?

Duplicates within each list are automatically removed before set operations. For example, if List A contains the same value twice, it is treated as a single entry.

What is the difference between 'All unique (A ∪ B)' and combining the other results?

The union contains all unique elements from both A and B. Combining Only-A + Only-B + Intersection gives the same set.

What happens with case-insensitive comparison?

All values are lowercased for comparison purposes. The displayed values retain the original casing of their first occurrence.

Can it handle very large lists?

JavaScript Set operations are used for efficiency, so tens of thousands of lines can be processed quickly, subject to browser memory limits.

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