GridCraft

Spreadsheets and data; an open-source, clean-room reimplementation of Microsoft Excel, rebuilt in pure Rust.

A fast, open-source, clean-room take on the Excel workflow. It runs natively on macOS, Windows, Linux and BSD, and in the browser via WebAssembly.
By the ArtCraft team.

GridCraft on getartcraft.com · ArtCraft · All Crafting Apps

_{Quarterly Sales Dashboard: a table with a totals row, conditional formatting, sparklines and two live charts — built entirely from GridCraft commands (File → New → Sample).}

[!NOTE] ArtCraft is a community of artists from all walks of life. Painters, photographers, filmmakers, illustrators, designers, animators, hobbyists, and people who picked up a pencil last week. If you make things, you're one of us. Come say hi on Discord.

A look around · Why GridCraft · Quick start · For agents · Architecture · Roadmap · The Crafting Apps · License and credits

A look around

Formatting. Accounting formats, cell styles, conditional rules and colour scales, frozen headers and a bar chart.	Formulas. 500+ functions, dynamic arrays, LET and LAMBDA, structured table references.
Dark mode and the Insert tab: tables, charts, sparklines, pictures, shapes, links and comments.	Charts. Column, bar, line, area, pie, doughnut, scatter, bubble, radar, histogram, waterfall, funnel, treemap, sunburst, box & whisker, stock and combo.

Why GridCraft

• Familiar. Excel's ribbon, formula bar, Name Box, sheet tabs, keyboard shortcuts, fill handle, point-mode formula entry with coloured references, Format Cells, Paste Special, conditional formatting, tables, charts and more. If you know Excel, you already know GridCraft.
• Compatible. XLSX is the native format: styles, themes, formulas (including dynamic arrays), tables, conditional formats, validation, comments, hyperlinks, charts, pictures, sparklines and print settings round-trip. CSV and TSV too.
• Capable. A dependency-graph calculation engine with dynamic arrays and spilling, 478 worksheet functions plus LET, LAMBDA, MAP, REDUCE, SCAN, BYROW, BYCOL and MAKEARRAY, structured table references, Excel's full number-format language, sort and AutoFilter, Flash Fill, data validation, outlining and subtotals.
• Fast. Copy-on-write workbooks (undo snapshots are nearly free), incremental recalculation, and a virtualised grid that only lays out what's on screen.
• Agent-native. Every ribbon button, menu item, dialog, keystroke and mouse gesture is a command that agents can run over a JSON control channel, an MCP server, or the CLI.
• Everywhere. One Rust codebase for desktop and the web. No subscription, no licence server, no telemetry.

Quick start

cargo run --release -p gridcraft                              # desktop app
cargo run --release -p gridcraft -- --sample sales            # open a sample (sales, budget, grades)
cargo run --release -p gridcraft -- book.xlsx                 # open a workbook
cargo run --release -p gridcraft -- --sample sales --control 7979   # + JSON control channel
cargo xtask ci                                                 # fmt, clippy, tests, assets, layering, wasm

Web

cd apps/gridcraft-web && trunk build --release     # → dist/web (serve it with any static server)
cd apps/gridcraft-web && trunk serve --release     # http://127.0.0.1:8771  (?sample=sales opens a sample)

You need trunk and the wasm32-unknown-unknown target. Open uses the browser's file picker (dropping files works too) and Save downloads the workbook.

For agents: MCP, CLI and the control channel

claude mcp add gridcraft -- gridcraft-cli mcp                 # headless MCP server
gridcraft-cli mcp --connect 7979                               # MCP bridged to a running window
gridcraft-cli eval '=XLOOKUP("b",{"a","b"},{1,2})'             # → 2
gridcraft-cli run --sample budget --cmd 'home.bold={"range":"B4:F4"}' --out budget.xlsx
gridcraft-cli cat budget.xlsx --range B4:F15                   # aligned text table
gridcraft-cli commands --search chart                          # every command and its params

The MCP server offers tools such as read_range, write_range, set_cell, evaluate_formula, format_range, insert_chart, create_table, sort_range, filter and execute_command (which reaches every one of GridCraft's commands). The desktop app's control channel adds real pointer and keyboard input, dialogs and screenshots. See docs/mcp.md, docs/cli.md and docs/control-protocol.md.

Architecture

GridCraft is an engine-first Cargo workspace with enforced layering (cargo xtask layers). The egui frontend is a separate crate, so the UI can be swapped without touching the engine.

Layer	Crates
L0	core (addresses, values, errors, dates, input parsing) · numfmt (number format codes)
L1	formula (lexer, parser, printer, reference adjustment) · functions (worksheet function library)
L2	model (workbook, sheets, copy-on-write cells, styles, tables, charts…) · calc (dependency graph, evaluator, dynamic arrays) · xlsx (XLSX and CSV)
L3	chart (toolkit-free chart layout and rendering)
L5	engine (session, commands, history, clipboard, fill, sort, filter, file I/O)
L6	ui-egui (Excel-style UI, control channel) · mcp (MCP server)
L7	apps/gridcraft, apps/gridcraft-cli, apps/gridcraft-web

• Contributor and agent rules (clean-room, asset policy, never-crash, quality gates): AGENTS.md
• Bundled assets: each one is listed with its licence in ATTRIBUTION.md
• Releases: signed macOS, Windows, Linux, BSD and web builds; see docs/releasing.md

Roadmap

GridCraft is pre-alpha and moving fast. Today it covers 60% of Excel's ribbon and menu commands (docs/parity.md) and about 93% of its worksheet functions. PivotTables, printing and PDF, page layout view, deeper chart formatting and scripting come next. The plan and estimates are in ROADMAP.md.

The Crafting Apps

GridCraft is one of the Crafting Apps: free, open-source creative tools from the ArtCraft team, each written from scratch in Rust and each able to stand on its own.

	App	What it's for	Code	Learn more
	PhotoCraft	Image editing: layers, masks, type and real PSD files	GitHub	Website
	VectorCraft	Vector illustration	GitHub	Website
	FilmCraft	Video editing, color and sound	GitHub	Website
	LightCraft	Photo library and raw development	GitHub	Website
	PrintCraft	Reading, organizing and protecting PDFs	GitHub	Website
	EffectCraft	Motion graphics and visual effects	GitHub	Website
	DesignCraft	Page layout and publishing	GitHub	Website
	GridCraft	Spreadsheets and data · you are here	GitHub	Website

And ArtCraft itself, our AI image and video studio for artists who want real control.

Come make things with us

Our Discord is where artists of every kind hang out: people who paint, shoot, draw, cut film, set type, and people still figuring out what they like to make. Share what you're working on, ask for help, tell us what's broken, or tell us what you wish these tools could do. Whatever your medium and however long you've been at it, you're welcome here.

discord.gg/artcraft · getartcraft.com · The Crafting Apps · GridCraft

License and credits

GridCraft is dual-licensed under MIT or Apache-2.0, at your option. Copyright (c) 2026 ArtCraft Team and the GridCraft contributors. Required notices are in NOTICE.

Bundled fonts, icons, images and other assets keep their own open licenses; each one is listed with its author, source and license in ATTRIBUTION.md.

All UI icons are drawn in code and are original; the sample workbooks and every screenshot in this README were made with GridCraft itself. GridCraft bundles no fonts: it uses the fonts installed on your system.

The ArtCraft name, wordmark and logos in docs/brand/ are trademarks of the ArtCraft Team and are not covered by this license. They may be used only unmodified, and only as part of this repository and GridCraft, under docs/brand/LICENSE-brand.txt. Forks and modified versions must remove them.

_{Microsoft, Excel and Microsoft 365 are trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. GridCraft is an independent, open-source project and is not affiliated with, sponsored by or endorsed by Microsoft Corporation; these names are used only to describe the workflows it is compatible with.}

_{Made by the ArtCraft team and community.}