List Diff — Find the Difference Between Two Lists Instantly
Paste two lists below and the tool immediately shows you what's different, what's missing, and what's shared — no sign-up, no file upload, 100% free.
Use the List Diff Tool Free →What Is a List Diff?
A list diff (short for list difference) is a comparison that shows you exactly how two lists differ. Given List A and List B, a diff breaks down into three parts:
- Only in A — items present in List A but missing from List B
- Only in B — items present in List B but missing from List A
- Common — items that appear in both lists
This is useful for any reconciliation task: comparing a before and after snapshot, checking which emails are on one list but not another, or finding which IDs are missing from a dataset.
Why Use This List Diff Tool?
- Instant resultsResults appear as you type — no "Submit" button needed.
- No upload, fully privateEverything runs in your browser. Your data never leaves your device.
- Any list formatNewline, comma, or semicolon separated. Excel paste works too.
- Export resultsDownload the diff as CSV, JSON, or a standalone HTML report.
- Fuzzy matchingCatch near-matches like typos or slight name differences.
- Case optionsToggle case-sensitive comparison on or off.
Common List Diff Use Cases
Email marketing: Diff your subscribers list against your unsubscribes list to find who should still receive emails.
IT & sysadmin: Diff server hostnames before and after a migration to find which servers weren't updated.
Data reconciliation: Diff an expected list of invoice IDs against what arrived to find missing records.
HR & payroll: Diff last month's employee list against this month's to see who joined or left.
Development: Diff two sets of feature flags or environment variables to spot configuration drift.
Frequently Asked Questions
What is a list diff?
A list diff shows you exactly how two lists differ — which items are unique to each list and which are shared. Paste your two lists above to see the diff instantly.
How do I diff two lists online for free?
Paste List A and List B into the tool above. It instantly calculates the diff with no sign-up, no file upload, and no cost.
What list formats are supported?
Any newline-separated list works. Comma-separated and semicolon-separated values are also supported. You can paste directly from Excel or Google Sheets.
Is my data safe?
Yes. All processing happens locally in your browser. No data is sent to any server, making it safe even for confidential lists.
Can I export the diff results?
Yes — export any result section as CSV or JSON. You can also export a full self-contained HTML report.