CSV is a flat grid of text with no data types; YAML is a structured, human-readable format used for configuration, fixtures and data files. This tool bridges the two: with a header row, each record becomes a YAML mapping (key: value) inside a sequence; without one, each row becomes a plain list of values. Quoted fields, embedded commas and line breaks, and escaped quotes are all parsed correctly.
Everything happens locally in your browser. Your data is never uploaded, logged or sent to a server, so it is safe to convert spreadsheets that contain private or sensitive records.