CSV Validator - Structural Well-Formedness Checker
Check a CSV file for consistent column counts and proper RFC 4180 quote escaping, with specific row numbers for any issues.
Paste or Upload CSV
Validation Result
Paste or upload a CSV file to check its structure.
Free CSV Validator — Structural Well-Formedness Checker
Paste or upload a CSV file and check whether it's structurally well-formed: consistent column counts across every row and properly escaped quotes per the RFC 4180 CSV convention. This tool checks structure only — it doesn't validate cell data types (like whether a column is really a number or date) or any business rules about what the data should contain.
How to Use It
Paste your CSV text into the box, or upload a .csv file directly. The tool scans every row and reports either a clean "valid" summary, or a specific list of issues with the row numbers where a column-count mismatch or a quote-escaping problem was found.
What It Checks
- Consistent column count — every row should have the same number of columns as the first (header) row; mismatched rows are flagged by row number.
- Quote escaping — a quote character appearing inside an already-started field without being doubled (
"") is flagged as malformed per RFC 4180. - Unterminated quoted fields — a quoted field that never finds its closing quote before the file ends is flagged.
Example
A file where the header row has 3 columns but row 4 only has 2 (a missing value with no trailing comma) gets flagged as "Row 4 has 2 columns, but the header/first row has 3."
Common Use Cases
- Checking an exported CSV file for missing or extra columns before importing it elsewhere.
- Debugging a CSV parsing error by finding exactly which row broke the format.
- Verifying a hand-edited CSV file didn't introduce an unescaped quote or a dropped comma.
FAQs
Does this check that my data types are correct?
No — this tool only checks structural well-formedness (consistent columns and proper quote escaping). It does not verify that a column meant to hold numbers actually contains numbers, or enforce any business rules about the data's content.
What counts as a properly escaped quote in CSV?
Per RFC 4180, if a field's value needs to contain a double-quote character, the whole field must be wrapped in quotes and the internal quote doubled — for example, a value of Say "Hi" should be written as "Say ""Hi""" in the CSV file.
Is my CSV data uploaded anywhere?
No — parsing and validation happen entirely client-side in your browser. Your file is never sent to a server.