Find mixed numbers dates and text in CSV columns

Step-by-step approach

Identify which fields are identifiers and which are quantities or dates.
Run the data type audit without altering the source.
Review blank, number, ISO date and text counts per column.
Do not coerce IDs into numbers when leading zeros matter.
Fix inconsistencies in a copy using validated business rules.

Try the matching tool

Open CSV Data Type Audit to work on a local copy. Review the result before importing it elsewhere.

What this does not solve

Browser tools can validate known structures and transform available data, but cannot restore deleted or corrupted bytes, infer unknown business facts, or guarantee that a target system will import every field as intended.