Compare lists online
Free list compare and list diff for List A vs List B. Paste or upload TXT, CSV, or JSON—the comparison stays in your browser.
Tool
How it works
- Paste two lists, upload a file, or try Example to see a sample.
- Adjust spaces, letter case, and blank lines if you need to.
- Compare, then check what’s only on one side and what’s on both.
- Copy the results or download them as
.txtor.csv.
Good for
- IDs, emails, usernames, or any list with one value per line.
- Columns copied from Excel or Google Sheets.
- Files on your computer—no account signup required.
- Instagram followers vs following from your official download.
Quick answers
What does A only mean? In List A, but not in List B.
Why can the counts look different? Line counts include blank lines. The compare count is unique values after cleanup.
When should I use CSV first-column mode? When each row has several columns and you only care about the first one (like an ID).
Can I upload JSON files? Yes—including common Instagram followers/following downloads. Usernames are pulled out for you.
What is ListDiff?
ListDiff (often searched as list diff or listdiff) is a free list compare tool. Put values in List A and List B, then see what’s only on one side, what’s in both (Intersection), in either (Union), or in exactly one list (symmetric difference)—plus duplicates if you need them.
Use it when you want to compare lists from spreadsheets, files, or Instagram downloads and know what’s missing, what’s extra, or what matches. Everything runs on your device, so you can try settings without waiting on a server.
A only / B only
What’s on one side but not the other—the usual place to start when something doesn’t match.
Intersection
What’s on both sides—shared IDs, mutual follows, or confirmed matches.
Duplicates
Values that repeat inside the same list—handy before you trust a “missing” result.
When this tool helps
- Two lists of users, SKUs, emails, or codes—one item per line.
- An “expected” list vs an “actual” list from spreadsheets or CSV files.
- A clean list of differences you can copy or download.
- Followers vs following without logging into a third-party app.
Featured tools and guides
Compare two lists
List A vs List B with clear only-in-one and in-both results.
Compare lists online
No account—paste or upload and keep the compare on your device.
Compare 2 lists in Excel
Find differences, matches, and duplicates from two spreadsheet columns.
Also: list difference checker · list comparison tool · is ListDiff safe?
Compare Instagram lists
Download your data, then compare followers and following—no extra app login.
Compare followers to following
See mutuals, who doesn’t follow back, and who you haven’t followed.
Who doesn’t follow you back
Following on one side, followers on the other—then check who’s only on following.
FAQ
What is ListDiff / list diff?
ListDiff is the name of this free list diff tool—compare two lists in your browser for differences, matches, and duplicates. If you searched “list diff” or “listdiff,” you’re in the right place.
Is ListDiff safe?
Yes. Comparisons run in your browser. See Is ListDiff safe? and Privacy.
Do you upload my lists?
No. The comparison stays on your device. See Privacy.
Why is my intersection empty?
Usually spaces, letter case, blank lines, or how the paste was split. Try trimming spaces and check the Excel paste tips.
Is this related to Instagram follower tools?
ListDiff is a general compare tool. If you can get names or IDs into text, you can compare them here—without connecting any third-party account.
What file formats can I compare?
Paste plain text, or import .txt, .csv, and
.json. Instagram followers/following JSON works too—usernames are pulled out for you.
What does symmetric difference mean?
Everything that’s only in one list—A-only and B-only together in one view.
Can I compare two lists of IDs or emails?
Yes. Paste or upload both sides with one value per line, then check what’s only on one side and what’s on both.
Can I check who doesn’t follow me back on Instagram?
Yes. Put Following in List A and Followers in List B. A only is who doesn’t follow back; Intersection is mutuals. See the full walkthrough.