About

Group the table.
Keep the meaning visible.

Groupgrain is one focused browser-local tool for turning a small pasted CSV table into per-key counts and exact decimal totals.

A materials list or activity table often needs a quick category summary. This tool keeps that operation inspectable: one key column, one different numeric column, first-appearance group order and complete record counts. It does not guess which names should match or which missing records should be discarded.

Exactness with a boundary

The CSV reader uses quote states so commas and line breaks inside quoted fields remain part of the field. The decimal model adds scaled integers, preserving values such as 0.1 and 0.2 exactly. Counts and sums are checked for conservation across the complete result. Strict input limits bound the table size; the guide explains the precise dialect rather than promising universal spreadsheet compatibility.

Exact arithmetic does not prove that your source data is correct or suitable for accounting. The tool has no knowledge of units, currencies, reconciliation, financial rules or the intended meaning of a negative adjustment. You choose the relevant table and columns.

Simple, local interaction

There is no account, upload service, payment or cloud project. Paste text, read its numbered columns and calculate. Edits invalidate old results. Up to 100 groups appear per page, while totals and optional local notes include all groups. Keys are text, including formula-looking and prototype-looking strings; there is no formula interpreter.

A free tool with checkable examples

The worked examples cover quotes, decimal tenths, multiline keys, duplicate headers and empty keys. Independent valid-fixture parsing and rational sums, strict malformed-state tests and actual source-handler tests check the implementation. Actual browser and public-host evidence remain separate release steps.

This release has no analytics, advertising or consent-platform loader. For a compact bug example or privacy question, use contact. The calculator works without contacting anyone, and no response time or outcome is promised.