CSV Formatter & Cleaner
Format and clean CSV data — convert delimiters, trim whitespace, remove empty or duplicate rows, and convert to Markdown tables.
CSV Validator
Validate CSV structure and data types, with per-cell error highlighting. Checks column counts, data types, empty rows, and duplicate headers.
Input data is processed in your browser
Data is never sent to a server
Tool
What is the CSV Validator?
This tool validates the structure and data quality of a CSV file and highlights exactly where the problems are.
Unlike the CSV Formatter — which reformats and converts CSV data — this tool focuses on verifying it. It checks for column count mismatches, empty rows, type violations, and duplicate or missing headers, then displays the results in a grid with per-cell error highlighting. Use it to catch data quality issues before importing a CSV into a database, spreadsheet, or application.
How to Use
- Paste your CSV into the input field. Validation runs automatically and any issues are listed immediately.
- Enable "First row is header" to treat row 1 as a header row and detect duplicate or empty header names.
- Enable "Flag column count mismatches" to report rows that have a different number of columns than the first row.
- Enable "Data type checks" to assign type rules (number, integer, email, date, URL, non-empty) to individual columns.
- The grid preview highlights problem cells in red. Hover over a highlighted cell to see the error message.
- Click "Copy report" to copy a plain-text validation report to your clipboard.
FAQ
How is this different from the CSV Formatter tool?
The CSV Formatter is for reformatting and converting CSV data. This validator is focused on checking data quality — identifying where problems are and reporting them, without modifying the data.
What is the difference between errors and warnings?
Errors (red) indicate problems that affect data accuracy, such as column count mismatches or type violations. Warnings (yellow) flag issues that are worth fixing but are not critical, such as empty rows or leading/trailing whitespace.
What date formats are recognized by the "Date" type check?
Formats like YYYY-MM-DD, YYYY/MM/DD, DD-MM-YYYY, and DD/MM/YYYY are supported. Formats that include a time component (e.g. ISO 8601 with time) are not currently supported.
Does the grid preview show all rows?
The grid shows up to 100 rows. Errors beyond row 100 are still reported in the error details list.