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Compare Lists

Paste two lists to see what's only in the first, only in the second, in both, and repeated within each. Your lists are compared locally in your browser and are not uploaded to Q3 Labs.

  • Free
  • · No signup
  • · Nothing uploaded
  • · Up to 200,000 items per list

Private by design. Your lists are compared locally in your browser and are not uploaded to Q3 Labs.

0 items

0 items

One item per line. Blank lines and spaces at the start or end of a line are ignored. Up to 200,000 items or 2,000,000 characters per list; long lists are compared when you press Compare Lists (or Ctrl + Enter).

Matching

Comparison

List A
0 items
0 unique
List B
0 items
0 unique
In both
0
Only in A
0
Only in B
0
Duplicates A
0
Duplicates B
0

Paste a list into List A and List B, one item per line, to compare them.

Free online list comparison tool

Comparing two lists by eye is slow and easy to get wrong. This tool does it exactly: paste email addresses, product codes, names, URLs, keywords or any other one-per-line list into each box, and it sorts every item into only in List A, only in List B or in both, and points out items repeated within a list.

You can copy any section, copy a full plain-text report or download everything as CSV. Nothing is guessed: two items match only when they are the same text, ignoring capitalization and surrounding spaces unless you say otherwise.

How to compare two lists

  1. Paste the first list into List A, one item per line.
  2. Paste the second list into List B.
  3. Choose how to match: ignore case (default) or case sensitive, and whether to normalize spaces inside items.
  4. Read the summary and the five result sections. Search or sort them if the lists are long.
  5. Copy or download the section you need, or the whole comparison.

Swap Lists exchanges the two boxes, which flips "only in A" and "only in B".

How list comparison works

Each list is split into lines. Blank lines are skipped and spaces at the start and end of each line are removed. Then every item gets a matching key:

  1. Unicode is normalized (NFC), so identical-looking characters typed differently match.
  2. Runs of spaces inside the item become one space, only if Normalize internal whitespace is on.
  3. The key is lowercased, unless Case sensitive is on.

The unique keys of each list are then compared as sets. Only in A is A minus B, only in B is B minus A, and in both is the overlap. Each item is shown once per section, exactly as it first appeared.

Find items only in List A

"Only in List A" lists items that never appear in List B, in the order they first appear in List A. Use it to find what's missing from the second list: customers not yet contacted, products missing from a new price list, or pages absent from a sitemap.

Find items only in List B

"Only in List B" is the reverse: items that are new in the second list, in List B's own order. Comparing an old list (A) with a new one (B), this is what was added, and only in A is what was removed.

Find common items

"In Both Lists" lists every item that appears at least once in each list, in List A's order. Each common item appears once, so repeats don't inflate the count.

Find duplicate items

Duplicates are checked within each list separately. For the list apple, banana, apple, orange, banana, the duplicates are apple (2×), banana (2×). The list has 5 items, 3 of them unique.

An item that appears once in each list is common, not a duplicate. To remove duplicates, copy the unique items from a comparison against an empty list.

Case-sensitive vs case-insensitive comparison

With the default, Ignore case, Apple in List A and apple in List B match: in both = Apple, shown as it was written in List A. With Case sensitive they don't: only in A = Apple, only in B = apple.

Use Case sensitive for codes, IDs, passwords or anything where capitalization changes the meaning.

How whitespace is handled

Leading and trailing spaces and tabs never matter, and blank lines are ignored. Spaces inside an item do: New York and New York are different items by default, and match with Normalize internal whitespace turned on. The item text itself is never changed.

Comparing large lists

Each list can hold up to 200,000 items or 2,000,000 characters. Items are looked up in a hash table rather than compared pair by pair, so the work grows in line with the list size. Results update as you type up to 200,000 characters in total; above that, press Compare Lists. Each section shows its first 1,000 items, and copy and CSV always include everything.

Example: comparing two lists

This is the tool's Load Example, and the results it produces:

Two example lists and how they compare
List AList BResult
apple banana orange mangobanana orange grape pear

Only in A: apple, mango

Only in B: grape, pear

In both: banana, orange

Frequently Asked Questions

How do I compare two lists?

Paste the first list into List A and the second into List B, one item per line. The results appear straight away: items only in List A, only in List B, in both lists, and any duplicates within each list. For very long lists, press Compare Lists.

What does "only in List A" mean?

Items that appear in List A and never appear in List B. Each item is listed once, even if it appears several times in List A.

What does "only in List B" mean?

Items that appear in List B and never appear in List A, listed once each in the order they first appear in List B.

What does "in both lists" mean?

Items that appear at least once in each list. Each common item is counted once, however many times it repeats: if apple appears twice in List A and once in List B, it counts as one common item.

Can I find duplicates?

Yes. Duplicates in List A and Duplicates in List B show every item that appears more than once in that same list, with how many times it appears. An item isn't a duplicate just because it's also in the other list.

Does capitalization matter?

Not by default: Apple, apple and APPLE match. Choose Case sensitive to treat them as different items.

Does whitespace matter?

Spaces and tabs at the start or end of a line are ignored, and blank lines are skipped. Spaces inside an item do matter, so "New York" and "New York" (two spaces) are different, unless you turn on Normalize internal whitespace.

Can I compare lists containing numbers?

Yes, but they are compared as text, not as values: 1, 01 and 1.0 are three different items. A–Z sorting does put numbers in numeric order (2 before 10).

Can I compare Unicode or non-English text?

Yes. Hindi, Urdu, Arabic, Chinese, Japanese, accented letters and emoji all work. Text is normalized to Unicode NFC, so the same accented letter typed two different ways still matches. Accents are not removed: café and cafe are different items.

Can I compare large lists?

Yes, up to 200,000 items or 2,000,000 characters per list. The comparison uses fast lookups rather than checking every pair, so even the largest lists take a moment. Up to 200,000 characters in total, results update as you type.

Does the tool preserve the original item text?

Yes. Matching ignores case (by default) and surrounding spaces, but results show each item exactly as it was first written. If List A has Apple and List B has apple, the common item is shown as Apple.

Can I download the comparison?

Yes. Download CSV saves every section with the columns Category, Item, Count in A and Count in B. You can also copy each section, or the full report, as plain text. Everything is generated in your browser.

Is my list uploaded?

No. Your lists are compared locally in your browser and are not uploaded to Q3 Labs.

Is this list comparison tool free?

Yes. It is free and needs no account.

Can I compare two CSV files?

Not as files: the tool compares pasted text, one item per line, and doesn't open or parse CSV files. To compare one column from two spreadsheets, copy that column from each file and paste it into List A and List B. Pasting whole CSV rows compares each full row as one item.

Explore more

Count how often each word appears with the Word Frequency Counter, or count words and characters with the Word Counter and Character Counter. Clean up stray spacing first with Remove Spaces. Fix capitalization before comparing with the Case Converter, build test lists with the Text Repeater, or turn items into URLs with the Slug Generator. Working with data? Try the JSON Formatter, JSON Minifier, Base64 Encoder & Decoder and URL Encoder & Decoder. Browse all our free tools.

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