About CSV Sleuth

CSV Sleuth gives you two CSV snapshots side-by-side and asks you to identify the row that is missing, duplicated, or present only in one file. Every day everyone gets the same challenge so you can compare results. Topics include single-key and composite-key matching, quoted strings with embedded commas, whitespace traps, column reordering, and UTF-8 identifier edge cases.

Why it helps

• Build intuition for the most common data-sync bugs: dropped rows, duplicate inserts, key mismatches.
• Learn how quoting and whitespace can make identical-looking rows compare as different.
• Use the related CSV Join/Merge/Compare tool to investigate both snapshots in depth.

Runs locally in your browser. Progress is stored only in this browser.