c35234e5f5
* M12.AR6: honour the B1/B2 calendar prefixes in number formats (Hijri for B2) * M12.AR6: match Excel's B1/B2 behaviour measured in review Changes from a reviewer's Excel run (TEXT and Range.NumberFormat): - A [$-...] locale tag before B2 keeps the date Gregorian (prefix still hidden); B2[$-401] stays Hijri. - Any other unquoted B and digit (B3dd, dd/mm/yyyyB2, dd B2 mm), and B2 before a number format (B20.00), make the code invalid: TEXT gives #VALUE!, a cell shows General, as for a code over 255 characters. - Under B2, ddd and dddd show the Arabic weekday name (full name for both). - Serial 60 has no Hijri date: TEXT gives #VALUE!, a cell shows ####. - Serial 0 shows as serial 1 (29/08/1317). Also fixes a break from merging main: days_from_civil now returns 0 for day 0 and 29 February 1900, which sent serials 0 and 60 to 1970 (23/10/1389) under B2. The Hijri day count no longer passes those dates. Docs: localization-parity states the behaviour, including the one measured case not matched (mmmm next to dddd prints the weekday in Excel). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> * M12.AR6: Hijri leap year in cycle year 15, not 16, as Excel shows A reviewer compared Excel's B2yyyy-mm-dd on 43,512 serials with this formula: it disagreed by one day on 1,372, all in cycle years 15 and 16, and moving the leap year from 16 to 15 left no disagreement. The leap years are now 2, 5, 7, 10, 13, 15, 18, 21, 24, 26 and 29 (still 10,631 days a cycle). The count of leap years before a year becomes (4 + 11y) div 30; it differs from the old (3 + 11y) div 30 only when y = 16 (mod 30), which is exactly the move from 16 to 15. The inverse's year estimate can now be one year off at a boundary and is corrected by one step. Tests: Excel values for 2 March 2005 (1426-01-21) and 29 January 2006 (1426-12-29) plus the 1425/1426 year boundaries they imply, the reviewer's other anchors, and exhaustive checks: year, month and 30-year cycle lengths for Hijri years 1 to 10,000; day -> Hijri -> day round trip and day-by-day succession for every day from 1 Muharram 1 AH to one cycle past 31 December 9999; every 1900-system serial 1 to 2,958,465 (except 60). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> * M12.AR6: match B1/B2 details checked in Excel 16.0 build 20527 Compared GridCraft with Excel 16.0 (build 20527, en-US) through COM: TEXT with B2dd/mm/yyyy on every serial from 1 to 2,958,465 (no difference), and about 1,750 format/value pairs through both a cell's NumberFormat and TEXT. Fixed what differed and is in scope: - Two-word Hijri month names use a no-break space (U+00A0), as Excel does. - B1 before a number format is rejected like B2 (B10.00, B1#,##0). - Prefix runs: a repeated prefix is accepted (B2B2, B2b2, [Red]B2B2, B1B1); a mixed one (B1B2, B2B1), more digits (B12, B21, B02), a prefix after a tag or space (B2[Red]B2, B2 B2) and an escaped \B2 are rejected. - Serial 60 under B2 is #VALUE! for any date or clock part (hh:mm, ss, AM/PM), not only date parts; [h] and literal-only sections still show. Regression tests use the Excel values (all 12 month and 7 weekday names, the accepted and rejected codes, serial 60). Not changed, listed in the docs: Excel's weekday/month-name mix-ups when ddd(d) and mmm(m) share a B2 section, weekday-only B2 sections (real weekday for serials 0-59, #VALUE! for the last days of 9999), and Buddhist-year b/bb/bbbb tokens. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com> Co-authored-by: FredApps <153173854+FredApps@users.noreply.github.com> Co-authored-by: FredApps <FredApps@users.noreply.github.com>
GridCraft
Spreadsheets and data; an open-source, high-performance modern spreadsheet application, built in pure Rust.
A fast, open-source, clean-room take on modern spreadsheet workflows. 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. |
 Pivot tables. Field list, filters, layouts, date grouping and show-values-as, saved to and read from XLSX. |
 Charts. Seventeen chart types, Chart Design tab and a Format pane; selecting a chart outlines its source data. |
 Page Break Preview, print settings, and PDF export and printing. |
Why GridCraft
- Familiar. 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. Everything is right where you expect it.
- Compatible. XLSX is the native format: styles, themes, formulas (including dynamic arrays),
tables, conditional formats, validation, comments, hyperlinks, charts, pictures, sparklines,
pivot tables and print settings round-trip. CSV and TSV too.
Legacy 97-2003
.xlsworkbooks open with their values, formulas and number formats (formatting and objects not yet). XLSB worksheet data can be imported, using saved values instead of formulas. ODS worksheet data can be imported, using saved values instead of formulas. Static pictures can live inside cells, fitting their size and moving with the data. - Capable. A dependency-graph calculation engine with dynamic arrays and spilling, 500+ worksheet functions plus LET, LAMBDA, MAP, REDUCE, SCAN, BYROW, BYCOL and MAKEARRAY, structured table references, a comprehensive 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
Choose Español under View → Interface language for Spanish formula names, decimal commas, and semicolon arguments. Workbooks, clipboard exchange, and programmatic APIs retain canonical English syntax.
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.
Ribbon access keys
Press and release left Alt on Windows/Linux/BSD, or press F10 on any platform, then type a sequence below one key at a time. Keytips appear on the supported Home controls and menu items. On macOS, use F10 (Fn+F10 if required by your keyboard); Option remains available for entering accented characters.
| Sequence after Alt/F10 | Action |
|---|---|
H A L / H A C / H A R |
Align left / center / right |
H V S or legacy E S |
Open Paste Special |
H O I or legacy O C A |
AutoFit selected columns |
In Paste Special, T/V/F/C select formats/values/formulas/comments, and E toggles Transpose. Enter applies the selected options; Escape cancels the dialog. These letters also work with Alt held on Windows/Linux/BSD.
Escape backs out one keytip level; Alt/F10 again exits keytips. Clicking, scrolling, or switching windows cancels navigation. Access keys do not start while editing text or using another dialog. This is initial support for these Home and legacy paths; other ribbon commands and full mouse-free navigation remain to be implemented. Browsers or desktop environments may reserve Alt/F10 for their own menus.
Logs
The desktop app writes its log to standard error and to gridcraft.log in the logs folder
next to its settings: ~/.config/gridcraft/logs on Linux and BSD ($XDG_CONFIG_HOME/gridcraft/logs
when set), ~/Library/Application Support/GridCraft/logs on macOS and
%APPDATA%\GridCraft\logs on Windows. Each start moves the previous log to gridcraft.1.log and
that one to gridcraft.2.log, so the log of a run that crashed survives the next start; attach
them to a bug report. A log file stops growing at 16 MiB. By default GridCraft's own crates log
at info and everything else at warn; RUST_LOG replaces that with env_logger-style
directives, e.g. RUST_LOG=debug or RUST_LOG=warn,gridcraft_engine=debug (a trailing *
matches a prefix: gridcraft*=debug). Runs with GRIDCRAFT_NO_PREFS set (no saved settings)
log to standard error only.
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, CSV, plus XLSB and ODS data import) |
| L3 | chart (toolkit-free chart layout and rendering) |
| L5 | engine (session, commands, history, clipboard, fill, sort, filter, file I/O) |
| L6 | ui-egui (spreadsheet 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 in alpha: the core workflow works end to end, but depth, fidelity and file
compatibility are still rough. It covers 89% of standard ribbon commands in our catalog
(docs/parity-checklist.md) and 513 standard worksheet functions
(docs/function-parity.md); this is a parity inventory, not a count of working implementations. Weighted by what spreadsheet users rely on, we
estimate it is about 50% ready for real work. Next up: XLSX fidelity on real-world files, very large
workbooks and multi-threaded recalc, chart depth, text in every script, and .xls import. Stage,
numbers and estimates are in ROADMAP.md; the ranked work list is docs/gaps.md.
Downloads
Download GridCraft from GitHub: the latest release has every build listed below, and all releases has earlier versions and their notes. <ver> in the file names is the version number, and SHA256SUMS.txt lists a checksum for every file.
Windows
| Build | Installer | Portable |
|---|---|---|
| x64 (64-bit Intel/AMD) | gridcraft-<ver>-windows-x64.msi |
gridcraft-<ver>-windows-x64-portable.zip |
| arm64 (Snapdragon and other ARM PCs) | gridcraft-<ver>-windows-arm64.msi |
gridcraft-<ver>-windows-arm64-portable.zip |
| x86 (32-bit) | gridcraft-<ver>-windows-x86.msi |
gridcraft-<ver>-windows-x86-portable.zip |
Installers and executables are code-signed. The MSI installer offers an optional desktop shortcut (unchecked on a new installation).
If the app doesn't open on Windows: the desktop app initializes only DirectX 12 by default.
Letting wgpu also create an OpenGL instance can crash some graphics drivers (AMD's
atio6axx.dll) before the window appears, so the app would flash in Task Manager and quit.
WGPU_BACKEND overrides the default for troubleshooting (for example dx12 or vulkan). In
PowerShell, from the folder containing the executable:
$env:WGPU_BACKEND = "vulkan"
& .\gridcraft.exe
Remove-Item Env:WGPU_BACKEND # restore the default for later launches
An explicit gl override can bring the driver crash back on affected systems, and vulkan can
bring back a crash in some Intel UHD Graphics drivers (igvk64.dll, #120). The macOS, Linux and
web backend defaults are unchanged.
If the app is slow on an older Windows PC, or DirectX 12 can't start: when DirectX 12 finds no
graphics card with a driver for it, it only offers the Windows-provided software renderer, which draws every
frame on the processor. In that case GridCraft uses OpenGL instead, without setting anything; if
the first renderer fails to start, it tries the other one once. The log file records the choice
(lines starting with graphics:). WGPU_BACKEND still overrides it (and then nothing else is
tried), e.g. $env:WGPU_BACKEND = "gl" or "dx12".
DirectX 12 shaders are compiled with FXC, which is part of Windows, so no dxcompiler.dll or
dxil.dll is needed, and a copy another program put on PATH can no longer stop the app at start
("Parent device is lost", #339). $env:WGPU_DX12_COMPILER = "dxc" (or "auto") selects wgpu's DXC
handling again for troubleshooting.
macOS
| Build | File | Notes |
|---|---|---|
| App, universal (Apple silicon + Intel) | gridcraft-<ver>-macos-universal.dmg |
Signed and notarized |
| Command-line tool, universal | gridcraft-cli-<ver>-macos-universal.zip |
Signed and notarized |
Linux
| Format | x86_64 | aarch64 (ARM64) | Notes |
|---|---|---|---|
| AppImage | gridcraft-<ver>-linux-x86_64.AppImage |
gridcraft-<ver>-linux-aarch64.AppImage |
Runs anywhere; updates itself with AppImageUpdate (.zsync files) |
| Flatpak | gridcraft-<ver>-linux-x86_64.flatpak |
gridcraft-<ver>-linux-aarch64.flatpak |
Sandboxed; flatpak install --user <file> |
| Debian/Ubuntu | gridcraft-<ver>-linux-x86_64.deb |
gridcraft-<ver>-linux-aarch64.deb |
|
| Fedora/RHEL/openSUSE | gridcraft-<ver>-linux-x86_64.rpm |
gridcraft-<ver>-linux-aarch64.rpm |
|
| Tarball | gridcraft-<ver>-linux-x86_64.tar.gz |
gridcraft-<ver>-linux-aarch64.tar.gz |
Unpack anywhere |
FreeBSD
| Build | File |
|---|---|
| x86_64 | gridcraft-<ver>-freebsd-x86_64.tar.gz |
Web (WebAssembly)
| Build | File | Notes |
|---|---|---|
| Static site | gridcraft-web-<ver>.zip |
Runs in a modern browser; host it on any static server |
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 |
 |
PdfCraft | Reading, organizing and protecting PDFs | GitHub | Website |
 |
EffectCraft | Motion graphics and visual effects | GitHub | Website |
 |
DesignCraft | Page layout and publishing | GitHub | Website |
 |
FigCraft | Interface design and prototyping | GitHub | Website |
 |
WordCraft | Word processing and documents | GitHub | Website |
 |
SoundCraft | Audio recording and editing | GitHub | Website |
 |
DeckCraft | Presentations and slide decks | GitHub | Website |
 |
CADCraft | Computer-aided design | GitHub | Website |
 |
GridCraft | Spreadsheets and data | GitHub | Website |
 |
TextureCraft | 3D texture painting | GitHub | Website |
 |
Craft Anything | See how any software works, then build your own | GitHub | Website |
 |
SolidCraft | Parametric 3D CAD by Tangency Labs (community app) | GitHub |
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.
Made by the ArtCraft team and community.