Our Data Validator is a simple but powerful tool that helps you check your CSV and JSON files for errors. Whether you're preparing a list of leads for your CRM or cleaning up a product catalog, this tool lets you set custom rules to catch mistakes like missing values, invalid email formats, or wrong numeric ranges. It's fast, secure, and works entirely in your browser so your data never leaves your computer.

Key Features & Benefits

Custom Rule Types

Validate data using 9 different rule types including required fields, email, phone, number, date, and URL checks.

Custom Regex Support

Need to check for something specific? Use regular expressions (Regex) to validate custom ID formats or product codes.

Detailed Error Reports

Get a clear list of every issue found, including the row number, column name, and a helpful message explaining what's wrong.

100% Private

Your sensitive data stays on your device. All validation happens locally in your browser, so nothing is ever uploaded to our servers.

How to Use the CSV & JSON Data Validator - Free Online Error Checker

Upload Your File

Upload your CSV or JSON file to see a quick preview of your data headers and first few rows.

Set Your Rules

Choose which columns you want to check and add rules like 'must be an email' or 'must be a number'.

Run Validation

Click 'Run Validation' and our engine will scan every row of your data against your rules in seconds.

Review Errors

Check the final report to see exactly which rows have errors, what's wrong, and download a summary to fix them.

Practical Use Cases

Clean Lead Lists

Ensure your marketing lists are error-free before importing them into Salesforce, HubSpot, or any other CRM.

E-commerce Data

Check your product CSVs for missing prices, invalid URLs, or empty descriptions before updating your online store.

Developer Testing

Validate large JSON files against your database rules locally before submitting them to your API.

Data Migration

assigned a clear health score and find structural issues early when moving data between different systems.

FAQs

What is data validation and why is it important?

Data validation is the process of checking data quality and accuracy against predefined rules. It ensures your datasets don't contain errors like missing values, invalid formats (e.g., bad emails), or out-of-range numbers before you use them for analysis or import.

What validation rules can I apply?

You can apply 9 different types of rules to any column: Required (non-empty), Email check, Phone number check, Number validation, Date format check, URL validation, Text Length limits, Numeric Range limits, and Custom Regex patterns.

Does this tool support custom patterns (Regex)?

Yes! You can use the 'Regex' rule type to define your own custom regular expressions. This allows you to validate specific formats like SKUs, ID cards, product codes, or any other structured text.

How do I see the validation results?

After running validation, the tool provides a detailed report showing the total pass rate, number of valid/invalid rows, and a complete list of specific errors and warnings for each row and column.

Can I export the validation report?

Yes, you can download the full validation report as a text file or copy it directly to your clipboard. The report includes summary statistics and itemized errors.

Is my data private?

Completely private. The Data Validator runs entirely in your web browser using JavaScript. No file is ever uploaded to a server, so your sensitive data remains on your device.