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CSV Validator: Find Errors in a CSV File

This free tool checks a CSV for common problems before you import it. It finds rows with too many or too few columns, quote errors, empty and duplicate headers and blank lines, and gives the line number of each.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

A single stray quote can break a whole import. Checking a CSV first saves time and avoids half-loaded data.

Paste the CSV and read the list of problems.

How to Use This Tool

  1. Enter or paste your input in the box or boxes above.
  2. Choose the options, if there are any.
  3. Press the button to run the tool.
  4. Read the result and use the copy button where one is shown.

How the Calculation Works

The file is read character by character. The tool counts the cells in each row and compares them with the first row. It notes quotes that open but never close, quotes that appear inside unquoted cells, blank headers, repeated headers and empty lines, and reports each with its line number.

Worked Example

In name,age / Ann,30 / Bob the third line has 1 column but the header has 2, so the tool reports it.

Common Uses

  • Before database imports.
  • Checking exports from other systems.
  • Data cleaning.
  • Teaching CSV.

Tips and Common Mistakes

  • Fix the first error and check again.
  • Line numbers count real lines in the file.
  • A cell with a line break counts as one row.
  • Check the first result against a case you already know, so you can trust the tool for the rest.
  • Nothing you type leaves your device. The work is done by your browser, so it also works with a slow connection once the page has loaded.

Next, you may need the CSV sorter, CSV and JSON converter, JSON formatter and validator, string escape and unescape tool.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

RFC 4180 says each row should have the same number of fields, and fields with commas, quotes or line breaks must be in double quotes with inner quotes doubled.
By counting commas, semicolons, tabs and pipes in the first lines and picking the most consistent one.
No. It only means the structure is sound. The values still need checking.
They are reported as warnings, since many importers treat them as empty rows.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.