Pivot Table Builder

The pivot table builder turns a block of raw rows into a grouped, summarized table without opening a spreadsheet program. Paste comma- or tab-separated data into the text box, upload a .csv or .tsv file, or load the built-in sample set to see it working right away. Once the data is parsed, drag any detected field, or tap its plus button, into the Filters, Rows, Columns, or Values shelves. Fields in Values get an aggregation choice — sum, average, count, minimum, maximum, or count of unique values — and Rows or Columns can each hold several fields for nested, multi-level grouping.

Parsing compares delimiter counts on the header line to decide between commas and tabs, then reads the text character by character so quoted fields containing commas or line breaks are handled correctly. Each column is scanned to classify it as numeric, date-like, or text, which sets a sensible default aggregation when the field lands on Values. Building the table groups the filtered rows into row and column keys, aggregates each cell with a plain reduce over the matching records, and renders merged row headers for repeated group labels, with row and column totals recalculated independently rather than summed from visible cells.

Everything runs in the browser tab and nothing is uploaded anywhere, which also means nothing is saved between visits — reloading the page clears the data, shelves, and filters, so keep a copy of anything worth reusing. To stay responsive without a server doing the work, only the first 20,000 rows of a larger file are processed, with a note shown when that happens. Row and column groups always sort in a fixed ascending order, alphabetical for text and numeric for numbers, since there is no drag-to-reorder or custom sorting of the finished table.