CSV Validator — Structure Check & Preview

Every data row should have the same number of columns as the widest row (usually the header). A shorter row is often a stray line break or missing comma; a longer row is often an unescaped comma inside a value. The validator flags both.

RFC 4180 style: a field wrapped in `"..."` can contain commas and newlines; escape a literal quote inside as `""`. Quotes appearing after unquoted text produce a warning (interpreted as literal).

Auto-detect picks whichever candidate (`,`, tab, `;`, `|`) appears most in the first line. If your data's first line has more of a different character than your intended delimiter — pick it manually with the buttons.