Why two lists don’t match (and how to fix it)

Checklist

1. Trim — trailing spaces from Excel paste are the #1 false “missing” item.
2. Hidden characters — if the tool shows a yellow warning or “hidden chars” badge, click Strip hidden chars (non-breaking and zero-width spaces are common).
3. Case — turn Case off, or use the Lowercase button on both sides, unless codes must stay case-sensitive.
4. Blank lines — leave Ignore empty on, or remove blank lines from the box.
5. Header row — delete email / id if it isn’t data, or check Header when extracting a CSV column.
6. Wrong column — for CSV, pick Col N (often 1 for IDs) and Apply instead of comparing whole rows.
7. Duplicates — check Dupes in A/B before you trust counts.

What to click in the tool

• Under each list, the toolbar has Trim, remove blank lines, Lowercase, and Strip hidden (eye-off icon)—these edit the text in the box before you compare.
• The CSV bar (Row / Col / number / Header / Apply) works after a file import or on pasted multi-column text. Multi-column CSV uploads usually default to column 1.
• After Compare, if both sides have items but Intersection is empty, a tip appears with strip / lowercase shortcuts and a link back to this guide.

Wide exports? See compare CSV files by ID for a full Col N walkthrough.

Demo

With Case off and Trim on, most of the sample below should appear under Intersection.

FAQ