Question 1

How do I find duplicate rows in a CSV file online?

Accepted Answer

Upload your CSV file to this tool. The Issues tab shows every duplicate row with its row number and the row it duplicates. A preview table shows the first five duplicate pairs. Duplicate rows are highlighted in red in the Data Table. Use the Clean Data panel to remove all duplicates in one click and download the result as CSV or Excel.

Question 2

How do I check for null values in a CSV file?

Accepted Answer

Upload your CSV to this tool. The Issues tab shows every column that has null or empty values, along with the null count and fill rate percentage. The Overview tab shows a fill rate bar chart for all columns at once. Null cells are visually highlighted in the Data Table.

Question 3

Can I remove duplicate rows and download the cleaned file?

Accepted Answer

Yes. After uploading your file, if duplicates are detected a Clean Data panel appears. Click Remove Duplicate Rows to deduplicate the dataset. The row count updates immediately. Then use the CSV, XLSX or JSON download buttons to save the cleaned file.

Question 4

Does this tool work with Excel files?

Accepted Answer

Yes. Upload .xlsx or .xls files directly. The tool reads all rows from the first sheet and runs the full analysis including duplicate detection, null checking, type validation, outlier detection and numeric statistics.

Question 5

Is my data uploaded to a server?

Accepted Answer

No. All processing runs entirely in your browser using JavaScript. Your files never leave your device. This makes the tool safe for confidential data, internal company spreadsheets and personally identifiable information.

Question 6

What is a data quality score?

Accepted Answer

The data quality score from 0 to 100 measures the overall health of your dataset. A score of 90 or above means the data is clean and ready for analysis or import. Scores below 50 indicate significant problems like high null rates, many duplicates or widespread type mismatches that will cause errors in downstream tools like Power BI, SQL databases or reporting systems.

Question 7

What does a type mismatch mean?

Accepted Answer

A type mismatch occurs when a column mostly contains numbers but some rows have text values. For example, a sales amount column where 998 rows contain numbers but 2 rows contain the text N/A or null. Type mismatches break SQL imports, Power BI measures and any calculation expecting consistent numeric data.

Question 8

Can I analyze data from a REST API?

Accepted Answer

Yes. Switch to the API tab, enter any REST endpoint URL and optionally add a Bearer token. The tool fetches the JSON response, automatically flattens nested objects into columns, and runs the full analysis. Useful for profiling live API data before building dashboards or ETL pipelines.

CSV & Excel Data Analyzer

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Free CSV and Excel Data Analyzer Find Duplicates, Nulls and Errors Instantly