GridCraft integration for Nextcloud

Open and edit the files in your Nextcloud with GridCraft, the open-source, Rust-native spreadsheet app, without leaving the browser.

• Edit in GridCraft appears in the Files action menu of every Excel (.xlsx, .xlsm, .xlsb, .xls, .xltx, .xltm), OpenDocument (.ods), CSV and TSV spreadsheet you can read.
• Save (Ctrl/⌘+S) writes an .xlsx workbook back to Nextcloud, and Nextcloud keeps the previous state as a file version. A workbook opened from another format is saved as .xlsx: the first time, you pick the name and folder (it's offered next to the original), and later saves go to that file.
• Export as PDF asks for a name and folder in your Nextcloud the first time.
• If someone else changes the file while you have it open, saving asks whether to replace their version or save a copy.
• Read-only files (for example a share without edit rights) open normally; saving offers a copy.
• Optionally, clicking a workbook in Files opens it in GridCraft: tick Open workbooks here from Files in the editor's top bar.

GridCraft runs entirely in your browser as WebAssembly. Files go only between your browser and your Nextcloud; there is no extra server to run.

Requirements

• Nextcloud 33, 34 or 35
• A browser with WebGPU or WebGL2 (any current Chrome, Edge, Firefox or Safari)
• The web server must serve .wasm files as application/wasm. Nextcloud's own .htaccess does this on Apache; the recommended nginx configuration does too.
• Recommended: gzip or Brotli for application/wasm. GridCraft is fetched once and then cached.

Install

Until the app is in the Nextcloud App Store, the latest version is in CyberFox-81/nextcloud_plugins, whose README has step-by-step commands for Docker, Nextcloud AIO and regular servers. In short:

1. Download integration_gridcraft.tar.gz and extract it into your Nextcloud's custom_apps/ (or apps/) folder, so you have custom_apps/integration_gridcraft/appinfo/info.xml.
2. Make it readable by the web server user, e.g. chown -R www-data:www-data custom_apps/integration_gridcraft.
3. Enable it: sudo -u www-data php occ app:enable integration_gridcraft. In Docker: docker exec -u www-data nextcloud php occ app:enable integration_gridcraft.

To make GridCraft the click-to-open default for every user who hasn't chosen otherwise:

sudo -u www-data php occ config:app:set integration_gridcraft open_by_default --value=true --type=boolean

How it works

Files ── "Edit in GridCraft" ──▶ /apps/integration_gridcraft/edit/{fileId}   (src/editor.ts)
                                  │  WebDAV GET/PUT with the user's session
                                  ▼
                                <iframe> /apps/integration_gridcraft/frame?host=parent   (templates/frame.php)
                                  │  GridCraft (web/*.wasm) — postMessage bridge

The editor page downloads the file over WebDAV and passes it to GridCraft with postMessage. When you save, GridCraft passes the bytes back and the page uploads them with If-Match, so a newer version on the server is never overwritten without asking. A save in a format the opened file isn't in, and an export, ask for a name and folder with Nextcloud's own folder picker the first time; later saves under the same name go to the same file. The frame page is the only one whose Content Security Policy allows compiling WebAssembly.

GridCraft has the opt-in embedding bridge (?host=parent) this app uses since storytold/gridcraft#237, so the official GridCraft build is used as is; the protocol is in web/README.md.

Build from source

make js      # npm ci && vite build → js/
make wasm    # clone GridCraft, build → web/   (needs Rust, see below)
make dist    # → build/dist/integration_gridcraft-<version>.tar.gz

make wasm runs scripts/build-gridcraft-web.sh, which needs the wasm32-unknown-unknown Rust target, wasm-bindgen-cli at the version in GridCraft's Cargo.lock (0.2.129 at the pinned commit), and optionally wasm-opt from binaryen. Set GRIDCRAFT_REF to build another GridCraft commit, FAST=1 for quicker development builds, and CRAFT_FONTS_DIR to a clone of storytold/craft-fonts to embed the shared Japanese fonts.

For development, npm run watch rebuilds the scripts as you edit; symlink or copy the repository into custom_apps/integration_gridcraft of a test server.

Releasing to the App Store

One-time setup (see the App Store developer guide):

1. Create the app's key and certificate request, and keep the key private and backed up:

   mkdir -p ~/.nextcloud/certificates && cd ~/.nextcloud/certificates
   openssl req -nodes -newkey rsa:4096 -keyout integration_gridcraft.key -out integration_gridcraft.csr -subj "/CN=integration_gridcraft"

2. Submit integration_gridcraft.csr as integration_gridcraft/integration_gridcraft.csr in a pull request to nextcloud/app-certificate-requests. Save the signed certificate they reply with as ~/.nextcloud/certificates/integration_gridcraft.crt.
3. Register the app at apps.nextcloud.com/developer/apps/new with the certificate and this signature:

   echo -n "integration_gridcraft" | openssl dgst -sha512 -sign ~/.nextcloud/certificates/integration_gridcraft.key | openssl base64

Each release:

make js && make wasm
scripts/sign-release.sh --key ~/.nextcloud/certificates/integration_gridcraft.key \
  --cert ~/.nextcloud/certificates/integration_gridcraft.crt --docker nextcloud

The script code-signs the app with occ integrity:sign-app (borrowed from a running Nextcloud container, or --occ for a local install; --archive signs a prebuilt archive), packs integration_gridcraft-<version>.tar.gz and prints the App Store signature. Attach the archive to a GitHub release, then submit its download URL and the signature at apps.nextcloud.com/developer/apps/releases/new.

Every new version also goes to nextcloud_plugins, replacing the previous one, with that repository's script (from a clone next to this one):

../nextcloud_plugins/scripts/update-plugin.py build/dist/integration_gridcraft-<version>.tar.gz

Limitations

• GridCraft is young; see its roadmap for what's still missing.
• One person edits at a time. There is no live co-editing; concurrent saves are caught and you choose what happens.
• In the browser GridCraft saves workbooks as .xlsx. A spreadsheet in another format (.xls, .xlsm, .xlsb, .xltx, .xltm, .ods, CSV, TSV) is saved as a new .xlsx file and the original stays as it is.
• GridCraft doesn't run or keep VBA macros: it tells you when it drops them while opening a file.
• In the browser, Save As stores the workbook like Save, and Share › Save a Copy isn't available; to keep a copy under another name, copy the file in Files first.

License

This app is licensed under the AGPL-3.0-or-later. GridCraft, bundled in web/, is licensed under MIT OR Apache-2.0; its bundled fonts and assets carry their own open licenses (see web/GRIDCRAFT-ATTRIBUTION.md or web/GRIDCRAFT-NOTICE). This is a community integration based on GridCraft by the ArtCraft team, not made or endorsed by them.