Count Values in Parquet Files Online
Group and count rows by any column in Parquet files directly in your browser. Sort by frequency or value to find the most common entries — no upload required.
About this tool
Group and count rows in a Parquet file by any column. See how many rows share each unique value — sorted by frequency. A fast way to understand the distribution of categorical data.
Frequently Asked Questions
What does the count-by tool do with a Parquet file?
It groups rows by the unique values in a chosen column and counts how many rows fall into each group — equivalent to SELECT col, COUNT(*) FROM table GROUP BY col ORDER BY count DESC.
Can I count by multiple columns in a Parquet file?
This tool counts by one column at a time. For multi-column grouping use the SQL Query tool or the Aggregate tool, which supports GROUP BY on multiple columns.
How are results sorted in the Parquet count-by output?
Results are sorted by count descending by default, so the most frequent values appear first. You can re-sort the output using the Sort tool.
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.
Related Tools
Hash & Anonymise Columns in Parquet Files Online
Anonymise or pseudonymise columns in Parquet files by replacing values with MD5, SHA-256, or DuckDB hashes — directly in your browser. Useful for GDPR compliance and sharing data without exposing PII — no upload required.
Group Concatenate Parquet Files Online
Concatenate text values within each group in Parquet files directly in your browser. Group rows by a column and join the values of another column into a single delimited string — no upload required.
Truncate Dates in Parquet Files Online
Truncate date and timestamp columns in Parquet files to a chosen precision — year, quarter, month, week, day, hour, or minute — directly in your browser. Rounds timestamps down to the start of each period. No upload required.
Coalesce Columns in Parquet Files Online
Fill null values in Parquet files from other columns — return the first non-null value across up to 8 columns in priority order. Add the result as a new column. Runs entirely in your browser.
Add UUID Column to Parquet Files Online
Add a UUID column to Parquet files directly in your browser. Generate random UUIDv4 or time-ordered UUIDv7 identifiers for every row. Choose the column name and position — no upload required.