Find what matches.
Keep what matters.

Results contain unique matching keys, in first-appearance order. “In both” follows List A order. Duplicate counts are repeated occurrences beyond the first, using the current matching options. This is a set comparison, not a comparison of item quantities.

Exact mode compares Unicode strings without normalization: é and e + a combining accent differ. Ignore case uses JavaScript Unicode lowercase conversion, not full Unicode case folding or language-specific matching (ß does not match SS). Trimming uses JavaScript trim rules. Options change matching only; displayed and downloaded values keep the first original line from each list.

Empty input is zero items. CRLF, LF, and CR separate lines; one final line break ends the last item without adding another. Empty lines are ignored by default. With trimming, whitespace-only lines become empty for matching. Turn off “Ignore empty lines” to include an empty key; it is visibly labeled in results.

Each panel previews up to 200 unique items. TXT includes the full selected group, one original per line, with a final newline; “In both” uses List A originals. CSV includes both originals and occurrence counts, with quotes and formula-triggering cells prefixed with an apostrophe. That safety prefix changes those exported cells. CSV empty originals are distinguished by their nonzero count. Spreadsheet software may reinterpret CSV if edited or reimported.

Limits per list: 1,000,000 UTF-16 code units, 10,000 lines, and 10,000 code units per line. Each export is limited to 2,200,000 code units; oversized exports are refused rather than cut off.