How to compare List A and List B
- Paste or open the first collection in List A.
- Paste or open the second collection in List B.
- Choose whether to ignore case, spaces, blank lines, or duplicates.
- Select Compare lists, then copy the result group you need.
Where list comparison helps
- Reconcile subscriber, inventory, SKU, or customer exports.
- Find missing IDs between reports from two systems.
- Compare email, domain, keyword, and tag collections.
- Identify shared values before importing or cleaning data.
Understand the list difference results
Only in A shows values from the first list that are missing from the second. Only in B shows values from the second list that are missing from the first. In Both is the intersection: every value shared by List A and List B.
These separate result groups make the list difference checker useful for both directions of a reconciliation. You can copy one group without manually deleting matches from the output.
Practical list reconciliation examples
These examples use the tool defaults unless an option change is stated. Each value is entered on its own line.
Membership with duplicates ignored
List A
alpha beta beta
List B
beta gamma
Expected result
Only A: alpha Only B: gamma In Both: beta
The repeated beta is reported once because Ignore duplicates is on.
Reconcile occurrence counts
List A
beta beta
List B
beta
Expected result
Only A: beta Only B: — In Both: beta
Turn Ignore duplicates off. One occurrence is matched and the extra occurrence stays in Only A.
Case and whitespace decisions
List A
SKU-01 blue
List B
sku-01 blue
Default result
In Both: SKU-01 In Both: blue
Defaults ignore letter case and trim outer spaces. Enable Case sensitive for case-significant IDs; disable Trim whitespace only when spaces are part of the value.
Compare two Excel or spreadsheet columns
Copy the first column from Excel, Google Sheets, or a CSV file and paste it into List A. Paste the second column into List B. Each row becomes one list item, so you can find matches and missing values without writing a lookup formula.
Enable trimming when copied cells contain accidental spaces. Ignore letter case for names or email addresses when capitalization should not create a mismatch. Keep case sensitivity on for identifiers where uppercase and lowercase have different meanings.
Compare unique values or preserve duplicates
Leave Ignore duplicates enabled when you only need to know whether a value exists in either list. Turn it off when repeated entries matter, such as duplicate email addresses, products, transaction IDs, or search terms. With the option off, occurrences are paired one by one: matched copies appear in In Both and any excess copies remain on their source side. Preserve source order for auditing, or sort the results before copying them.
Related comparison tools
Compare free-form text online, compare JSON objects, compare YAML configuration files, or review source-code changes.
Frequently asked questions
How do I compare two lists and find the differences?
Paste one value per line into List A and List B, choose your matching options, and select Compare lists. The results separate values found only in A, only in B, and in both lists.
What do Only in A, Only in B, and In Both mean?
Only in A contains values missing from List B. Only in B contains values missing from List A. In Both contains values shared by the two lists.
Can I compare two Excel or spreadsheet columns?
Yes. Copy each column from Excel, Google Sheets, or another spreadsheet and paste it into a list box. Each spreadsheet row is treated as one item.
Can I compare email, SKU, domain, or keyword lists?
Yes. Any plain-text collection with one value per line works, including emails, SKUs, IDs, domains, keywords, tags, and inventory exports.
How does the list compare tool treat duplicates?
Ignore duplicates is enabled by default, so membership is reported once. Turn it off to reconcile occurrence counts: matching occurrences go to In Both, while extra copies remain in Only in A or Only in B.
Does list order matter?
Membership comparison does not depend on order. Results preserve the original List A or List B order unless you enable sorting.
Are my lists uploaded?
No. Your lists and text files are compared locally and remain in the current browser tab.