GridCraft

GridCraft is a free, open-source rebuild of the Microsoft Excel workflow in pure Rust: the ribbon, formula bar, Name Box and sheet tabs, keyboard shortcuts, the fill handle, point-mode formula entry with coloured references and Format Cells, Paste Special and conditional formatting. It runs natively on macOS, Windows, Linux and BSD and in the browser via WebAssembly, with no subscription, no licence server and no telemetry.

Underneath the grid is a real calculation engine: a dependency graph with incremental recalculation, dynamic arrays that spill, and more than 500 worksheet functions including LET, LAMBDA, MAP, REDUCE, SCAN, BYROW, BYCOL, MAKEARRAY and structured table references. It copies Excel's full number-format language, plus sort and AutoFilter, Flash Fill, data validation, outlining and subtotals. XLSX is the native format and round-trips faithfully — styles, themes, formulas, tables, conditional formats, validation, comments, hyperlinks, charts, pictures, sparklines, PivotTables and print settings all survive a save and reopen. CSV and TSV import and export, Excel 97–2003 .xls opens with values and formulas, and XLSB and ODS worksheet data can be imported from saved values. Seventeen chart types come with a Chart Design tab and a Format pane, and PivotTables support field lists, filters, layouts, date grouping and show-values-as, saved to and read from XLSX. There is Page Break Preview, print settings and PDF export.

GridCraft is agent-native: every ribbon button, dialog and mouse gesture is a command, and agents read, write, evaluate and format cells over an MCP server, a JSON control channel or the gridcraft-cli (eval, run, cat, commands). It is in alpha — covering 89% of the Excel ribbon commands and 513 of Excel's 523 worksheet functions, estimated at about 50% ready for real work — but for opening real XLSX books and calculating without a Microsoft 365 subscription, it already works.