A CSV validator checks your comma-separated data for structural integrity — consistent column counts, proper quoting, delimiter detection, and empty row warnings. Use it before importing data into databases, spreadsheets, or ETL pipelines to catch formatting errors that cause import failures. Paste your CSV or upload a file to validate instantly.
Validation Checks
Row Issues
Data Preview (first 10 rows)
CSV Format Rules (RFC 4180)
1. Delimiter: Comma by default. Each field is separated by one delimiter character.
2. Header row: Optional. If present, must have the same number of fields as data rows.
3. Quoting: Fields containing commas, newlines, or double quotes must be enclosed in double quotes (").
4. Escaping quotes: A double quote inside a quoted field is escaped by doubling it: "He said ""hello""".
5. Line endings: CRLF (\r\n) is the standard, but LF-only is widely accepted.
6. Consistent columns: Every row should have the same number of fields as the header row.
How to Validate CSV Files
A CSV validator catches structural problems before they cause import failures in databases, spreadsheets, or ETL pipelines. The most common CSV issues are inconsistent column counts, unclosed quotes, and wrong delimiter detection — this tool checks all of them automatically.
Step 1: Paste CSV or Upload a File
Paste your CSV data directly into the textarea, or click "Upload file" to load a .csv or .txt file. Files are read locally — they're never uploaded to any server. Large files may take a moment to process.
Step 2: Set the Delimiter
Leave "Auto-detect" selected to automatically identify the delimiter. The tool counts occurrences of comma, semicolon, tab, and pipe in the first 5 lines and picks the most consistent one. If the auto-detection is wrong, manually select the correct delimiter. European Excel exports typically use semicolons; TSV (tab-separated) files use tabs.
Step 3: Review Issues and Preview
The validator shows a VALID / INVALID / WARNINGS badge, validation checks, stats (row count, column count, delimiter, empty cells), and problem rows highlighted in the preview table. Click any row issue to understand what went wrong. The preview shows the first 10 rows rendered as an HTML table.
Fixing Column Count Mismatches
The most common error is "Row N has X columns, expected Y." This usually means a field value contains
an unquoted delimiter character. Fix it by wrapping the field in double quotes:
name,"address, city",age instead of
name,address, city,age.
FAQ
Is this CSV validator free?
Yes, completely free with no account required. Paste your CSV data or upload a file to validate instantly. All processing runs in your browser — your data never leaves your device.
Is my CSV data private?
Yes. Validation runs entirely in your browser. Your CSV data is never uploaded to any server, stored, or transmitted. You can safely use it with sensitive data.
What does this CSV validator check?
It checks: at least one row of data, consistent column count across all rows (flagging rows with different counts), unclosed double-quote pairs, empty rows (warning), and trailing delimiter characters. It also auto-detects the delimiter (comma, semicolon, tab, or pipe).
What is RFC 4180 and does my CSV comply?
RFC 4180 is the informal standard for CSV files: comma-delimited, optional header row, fields quoted with double quotes when they contain commas or newlines, double quotes escaped by doubling them ("" inside quoted fields). This validator checks the structural rules from RFC 4180.
Can I validate CSV with a semicolon or tab delimiter?
Yes. The validator auto-detects the delimiter by analyzing the first few lines. You can also manually override with the delimiter buttons (comma, semicolon, tab, pipe, or custom character). European Excel files commonly use semicolons as delimiters.
Why does a row show as having the wrong number of columns?
Column count mismatches usually mean a field contains an unescaped comma (without quotes), a missing closing quote, or the wrong delimiter was detected. Check the highlighted row and ensure fields with delimiters inside them are properly enclosed in double quotes.