# Free CSV Validator: Find Errors, Profile Columns | Dedupely

> Validate a CSV in your browser: unclosed quotes, short rows, blank and duplicate rows and bad encoding by line, then each column’s type, fill rate and range. Free.

- URL: https://dedupe.ly/tools/csv-validator
- Section: tools
- Site index: https://dedupe.ly/llms.txt
- Any page: append `.md` to its URL for this plain-text form

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## CSV validator and column profiler

Find the broken rows and see what every column holds.
[Use in Claude](https://claude.ai/customize/connectors?modal=add-custom-connector&connectorName=Dedupely%20free%20tools&connectorUrl=https%3A%2F%2Fdedupe.ly%2Ftools%2Fmcp)
CSV file
Or paste rows here
Validate
Free for 10 runs a day.

### Find the line that breaks the CSV

One unclosed quote swallows every row after it. The import fails or shifts columns. The error names no line.
**The validator lists every problem in the CSV with its line number.**

### Know each column before you import

A column called Email holds phone numbers. Half the Amount cells are empty. Nobody notices until a report is wrong.
**Every CSV column gets its type, fill rate, distinct count and range.**

### Use it from a script or an AI agent

[Use in Claude](https://claude.ai/customize/connectors?modal=add-custom-connector&connectorName=Dedupely%20free%20tools&connectorUrl=https%3A%2F%2Fdedupe.ly%2Ftools%2Fmcp)
MCP https://dedupe.ly/tools/mcp every free tool in one connector (this one: validate_csv)
POST https://dedupe.ly/tools/api/csv-validator
{ "csv": "Email,Amount\nann@x.example,1200\nbad-email,abc" }
Docs https://dedupe.ly/tools/api/openapi.json
[OpenAPI document](https://dedupe.ly/tools/api/openapi.json) ·
[API index](https://dedupe.ly/tools/api) ·
[llms.txt](https://dedupe.ly/llms.txt)

### Questions about validating a CSV

What does the CSV validator check?
Quotes that are never closed or sit in the wrong place, rows with too many or too few fields, blank and duplicate rows, empty or repeated headers, mixed line endings and broken characters.
What is in the column profile?
For each column: its type, how many cells are filled, how many values are distinct or repeated, how many do not fit the type, and its minimum, maximum and most common values.
Which types does it detect?
Email, URL, phone, date, whole number, decimal number, true or false, and text.
Why does a column show invalid values?
Most of the column fits one type and these cells do not, such as bad-email in a column of email addresses or 2026-02-30 in a column of dates.
What do the broken characters mean?
The file was saved in one encoding and read in another, so José shows as José. Save it again as UTF-8.
Is my file uploaded?
No. The CSV is checked in your browser and never leaves your computer.
Is it free?
Yes. Ten checks a day, free.

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### Get started for free

20 free trial merges and as much free support as you need to get your duplicates under control.
[Talk to sales](https://meetings.dedupe.ly/meetings/hampus-isaksson/dedupely-zoom-schedule)[Try for free](https://v2.app.dedupe.ly/signup)
[Or sign up with Google](https://v2.app.dedupe.ly/signup/google)
Running CRM cleanup for clients? [See the Partner Program](https://dedupe.ly/become-a-partner)
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