Paste two lists, choose matching rules, then get the shared lines plus quick stats.
Enter two lists below. Each item should be on a separate line.
Items that appear in both lists.
List intersection feels simple. Paste two lists, click one button, copy the overlap.
Yet most wrong results come from one of two things. Formatting drift. Matching rules you did not mean to apply.
This list intersection tool gives you four switches, so the output matches your intent. Case sensitivity, whitespace trimming, empty line removal, sorting.
Pick rules first. Then trust the overlap.
Intersection means one thing. A line appears in list 1. The same line appears in list 2. The output keeps one copy.
Everything else stays out.
If you need a combined list, use a union workflow instead. Try the List Union Tool when you want one de-duplicated list from two inputs.
If you need what is missing, take the opposite path. The List Difference Tool highlights items present in one list, absent from the other.
Those three operations solve different questions. Overlap. Combined set. Unique remainder.
Mixing them up wastes time.
Here is a fast way to choose the right one.
| Operation | What you get | Good for |
|---|---|---|
| Intersection | Lines present in both lists | Overlap checks, access audits, list cleanup |
| Union | All unique lines from both lists | Building a master list without repeats |
| Difference | Lines present in one list, missing from the other | Finding gaps, missing items, drift over time |
Need lines that show up once across a bigger merged list. Use Find Unique Lines after you combine sources.
Real work rarely arrives as neat data.
You paste usernames from a ticket. You export emails from a CRM. You copy product SKUs from a spreadsheet cell range. Then you need the common subset between two sources.
Some examples.
In each case, the best output depends on normalization. A trailing space should not break a match. Unless you want it to.
One realistic example. A vendor exports “ACME-1042 ” with a trailing space. Your internal list stores “ACME-1042”. With trimming on, you get a match. With trimming off, you get a miss. Neither output is wrong. Only one matches your goal.
The tool splits each input into lines. One line becomes one item.
Then it applies your rules.
Trimming removes leading and trailing spaces. Empty line removal drops blank entries. Case handling turns matching into either exact case matching or lowercased matching.
After normalization, the tool checks which normalized items appear in both lists. That part uses a set lookup, so it stays fast even when you paste long lists.
Finally, it formats the output. Sorting is optional. Stats show counts plus a match rate.
The match rate uses the larger list as the baseline. This is a practical signal, not a math proof of similarity.
If you want a quick sanity check, turn sorting on, copy the result, then spot-check three random items in each original list. This catches the most common paste mistakes fast.
Most “wrong” intersections are correct given the rules. The surprise comes from hidden differences in input.
Examples.
If you need field-level matching, first clean your input. A quick way is to convert structured text into one value per line, then rerun the intersection.
For a visual diff view, the Text Line Comparison tool helps when you need to see what differs inside a line.
This tool compares whole lines. It does not parse CSV columns. It does not detect synonyms. It does not fix typos.
If two items match only after heavy normalization, you need a different approach. Try a fuzzy matching workflow in your data tool, then validate results manually.
Also, treat case rules with care for IDs. Many identifiers are case-sensitive by design. API keys, coupon codes, file names on some systems.
When in doubt, run two passes. One forgiving pass for a quick scan, one strict pass for your final output.
Paste list 1 from the source you trust most. The tool preserves that side’s original line in the result.
Turn sorting off when you want the output to follow list 1 order. Turn sorting on when you want a clean scan list.
Need overlap across more than two lists. Run intersection iteratively. Output becomes list 1 for the next run.
For multi-list overlap, the Find Common Lines tool fits better when you have more than two sources.
Find overlapping customer segments, shared product features, or common data points across datasets.
Identify common factors, shared references, or overlapping findings across multiple research sources.
Match user permissions, find shared roles, or identify common access rights across different groups.
The tool splits each list by line breaks, applies your selected options for trimming and case handling, then removes empty entries.
Normalized items from both lists convert into sets. This structure enables fast lookup operations for comparison.
The algorithm checks each item from the first list against the second set, collecting matches into the result collection.
Common items sort alphabetically if requested, then display with statistics showing match rates and item counts.
Performance scales well for typical paste sizes. Thousands of lines stay responsive because lookup uses a set. If your browser tab slows down, split the job into smaller batches.
Privacy stays simple. Processing runs in your browser. Your lists do not get uploaded by this page logic.
Short, practical answers about matching rules, limits, and privacy.
Hidden whitespace is the usual cause. Keep “Trim Whitespace” enabled, then rerun. If you copied from a spreadsheet, trailing spaces are common.
Often yes. Codes, usernames, file names, and many identifiers treat case as meaningful. Use a strict pass for final checks, then store the output.
Whole lines. If you paste CSV rows, the full row becomes the item. For column-based matching, extract the column first, then run intersection.
Intersection is set-based. One match appears once. If you need counts of repeats, keep the raw lists elsewhere and treat this output as a unique overlap list.
No. The intersection logic runs in your browser on this page. Use the copy buttons to move results where you need them.
If you need the non-overlap, run the List Difference Tool. If you need one combined list, run the List Union Tool. Use the overlap as a clean input for the next step.
