Most duplicate tools upload your library or push "similar" matches. DupShelf runs entirely in your browser—photos never leave your device. Scan a folder (Chrome/Edge) or add batches. Exact duplicates are grouped by file content (SHA-256), so renamed copies and re-exports still match. Review groups, choose keepers, move extras to a subfolder or export CSV. DupShelf never auto-deletes. Free, no account, no upload—built for messy backups and downloads.