Get Top N Rows from CSV Files Online

What does top-N per group do to a CSV file?

It returns the top N rows within each group, ranked by the column and direction you choose — equivalent to SQL's ROW_NUMBER() OVER (PARTITION BY group_col ORDER BY rank_col DESC) with a WHERE row_num <= N filter. For example, the 3 highest-revenue customers per region.

Does top-N per group preserve all columns in the CSV output?

Yes. All columns from the original file are preserved. Only rows that fall outside the top N within their group are excluded from the output.

What happens when there are ties at the Nth position in a CSV top-N operation?

Ties are broken using row_number(), so one row from the tied group is arbitrarily selected and the others are excluded. To keep all tied rows at the boundary, use the SQL Query tool with RANK() and filter WHERE rank <= N.

Is my data private?

Yes — completely. Your file is never uploaded to any server. Everything runs locally in your browser using WebAssembly — processing happens entirely inside your tab. Once you close the tab, nothing is retained.

What is the maximum file size?

The free limit is 50 MB. For larger files, performance depends on your device's available memory — most modern machines handle 500 MB to 1 GB comfortably.