List Reconciler
Compare two lists — find what was added, removed, or duplicated. Perfect for reconciliation.
Reconciling two lists by hand is slow and error-prone. This tool does it instantly.
How to use
- Paste your two lists into Box A and Box B, one item per line.
- Copy directly from Excel or CSV — one column at a time.
- Click "Compare lists" to see what is only in A, only in B, and any duplicates.
About this tool
Common uses: comparing customer lists, inventory counts, attendance records, or any two datasets.
All processing happens in your browser — your data is never uploaded anywhere.
How it works
The reconciler treats each list as a set of lines and computes the difference: lines only in list A (removed), lines only in list B (added), and lines in both (unchanged). Duplicates inside a single list are flagged separately, since set logic would otherwise hide them.
Comparison is exact-match on the full line — run both lists through the Whitespace Normalizer first if they came from different sources with inconsistent spacing. Results are grouped so you can scan what changed at a glance.
Worked examples
Inventory: Compare last month’s 800 SKUs against this month’s to find the 12 discontinued and 30 new items.
Attendance: Diff the invite list against the RSVP list to see exactly who has not replied.
Frequently asked questions
Can I paste from Excel?
Yes. Copy one column from Excel or Google Sheets and paste it directly — each row becomes one list item.
Is my data uploaded?
No. Everything is processed locally in your browser using JavaScript. Nothing leaves your device.
What about extra spaces?
Leading and trailing spaces are trimmed automatically. Use case-sensitive mode if "Alice" and "alice" should be treated as different.
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