A small Python tool that cleans a messy CSV in one command: trims stray whitespace, drops fully-empty rows, lowercases email columns, and removes duplicate rows — or duplicates on one key column you choose (for example Email). Every run writes a plain JSON report next to your output showing exactly how many duplicates and empty rows were removed, so you can see what changed. Runs fully offline, no install beyond Python 3.9+, no account, no subscription. Includes: cleansheet.py, a messy sample CSV, its cleaned output + report (so you can see the before/after), and a README. Honest scope: it does not validate email deliverability, fix misspelled data, merge similar-but-not-identical rows, or guess missing values. Duplicates are exact matches after trimming (and email lowercasing).