Check before you import
- Add your file or paste CSV text. Confirm the delimiter, encoding and whether the first record contains headers.
- Select a unique key only if one column must identify every record.
- Run the check. Start with Errors, then review Warnings that may affect your values.
- Correct problems in the source, or preview a format-only export. Keep the report with your import notes.
Three levels, different actions
Errors break this checker’s structure or selected rules. Warnings identify things an importer may interpret differently. Info describes the file, including empty values that are not necessarily mistakes.
What a CSV check cannot know
A structurally consistent file can still fail a specific importer. This tool does not know that system’s required columns, allowed values, database state or business rules. Auto detection is a suggestion; a delimiter or encoding can be readable without being the intended one.
Quotes allow commas, quotes and line breaks inside a CSV field. They do not force a spreadsheet to keep an identifier as text. For IDs, postal codes and other exact strings, review the import type in your destination.
Technical references: RFC 4180, OWASP on CSV injection, and Microsoft on leading zeros and long numbers.
CSV validator FAQ
Does a clean report guarantee that my CSV will import?
No. The checker validates the selected CSV format and optional unique-key rule. Your importer may also require specific columns, types, values or records that already exist in its database.
Are my CSV files uploaded?
No. File contents are read and checked locally in your browser. The tool does not upload the CSV, save its contents or send cell values to analytics.
Will the checker fix or delete my data?
No changes happen automatically. Optional export can change encoding, delimiter, record endings and quoting after a preview. It preserves every cell value and record, then checks the output again. It does not trim values, delete duplicates or repair broken quotes.
Why are leading zeros and long IDs warnings?
Spreadsheet programs may convert numeric-looking values into numbers, removing leading zeros or losing digits in long identifiers. Import these columns as Text when the exact characters matter; CSV quotes alone do not guarantee a text type.
Which files and encodings are supported?
The checker accepts one CSV, TSV or text file, up to 5 MiB, 50,000 records, 200 columns and 500,000 cells. It supports comma, semicolon, tab and pipe separators; UTF-8 and UTF-16, plus manually selected Windows-1252 and Windows-1251. Original encoding cannot be checked for pasted text.
How are duplicate keys compared?
Choose one Unique key column to require nonempty, unique values. Comparisons are exact and case-sensitive: 001, 1, A, a and A followed by a space remain different strings. No normalization or numeric conversion is applied.