Casual Sheets is a self-hostable, browser-based spreadsheet that looks and behaves like Microsoft Excel — ribbon UI, formula bar, file-centric workflow — with real-time multi-user co-editing built in. Upload an .xlsx file, share a link, and edit together instantly. No accounts, no Microsoft / Google login, no lock-in — your data stays on your own server, in one Docker container.

Teams that need a self-hosted spreadsheet editor embedded inside their own product — an intranet, file manager, LMS, CRM, or private cloud — without sending data to Google or Microsoft. Use it as a standalone app or embed the editor as an SDK.

Maturity — 0.x: production-ready for small / self-hosted deployments; still evolving for enterprise-scale workloads. One box scales to thousands of concurrent editors (load-tested); see the CHANGELOG for what's stable.

Compares to: Google Sheets · Excel Online · OnlyOffice

Built on Univer OSS (Apache-2.0) — the OSS variant, never the Pro package — with a custom Office-style shell layered on top. Sister projects: Casual Editor (.docx) and Casual Slides (.pptx).

• Google-Docs-style title bar — logo + filename + classic menus (File / Edit / View / Insert / Format / Data) in a single chrome strip, right-edge panel rail for Tables / Charts / Outline / Comments / History
• Formula bar with an editable Name Box (jump to any cell by typing its address)
• Cell editing: inline edit, F2, formula entry, multi-line paste, cross-sheet references with autocomplete
• Fonts, colors, fill, borders (7 modes + color picker), alignment, wrap, merge/unmerge
• Rows + columns: hide/unhide, group/outline (collapse/expand), resize
• Freeze panes — top row, first column, or freeze at any selection
• Sort (single and multi-column dialog), Filter (AutoFilter + re-apply), Tables (Format as Table, named tables panel)
• Comments with corner indicator markers
• Conditional formatting, data validation, drawings — fully round-tripped and co-edit synced

• Charts — 8 types, drag-to-resize, format dialog with trendlines, date-axis detection, per-series colour overrides; collab-synced; PNG embed in .xlsx
• Pivot tables — group-by + multi-aggregations, filter fields, Refresh PivotTables, drill-down to source rows (Ctrl+Shift+D), Insert dialog
• Sparklines — in-cell mini-charts (line / column / win-loss) via Insert → Sparkline, persist through the __casual_sheets_sparklines__ resource
• Analysis tools — Name Manager (Ctrl+F3), Flash Fill (Ctrl+E), Goal Seek (iterative solver)
• Show Formulas (Ctrl+`) — non-destructive overlay paints formula source on every formula cell
• Print Area — A1 field in Page Setup + File-menu "Set / Clear Print Area"
• Paste Special (Ctrl+Alt+V) — All / Values / Formulas / Formats / Column widths / All except borders
• Recent Files — IndexedDB landing screen surfaces the last 10 workbooks on a blank Untitled
• Version history — auto-snapshots every ~10 min while dirty + "Save version…" manual entries; preview a snapshot then Restore (captures a "before restore" crumb for undo)
• Dark theme — title-bar sun/moon toggle, bridged to Univer's ThemeService so the canvas chrome flips too
• Status-bar customisation — right-click selection stats to toggle which appear (Average / Count / Sum / Min / Max / Numerical Count)
• Sheet tabs: add, rename, delete, reorder, color; tab strip refreshes live when peers act
• Autosave to IndexedDB with a restore banner if the tab closes unexpectedly
• Dynamic workbook growth — starts at 1024×26, expands to 8192×1024 on demand
• File → Properties dialog, Help → Report a Bug (GitHub issue prefill)
• Inline SVG icons (~155 components) — sharp at every size, no font-load delay

• Parsed and serialised entirely in Web Workers — the main thread never blocks on multi-MB files
• ODS round-trip: styles, dimensions, freeze, hyperlinks, comments, defined names
• xlsx round-trip: conditional formatting, data validation, drawings, tab colors, named ranges, hyperlinks (inline cell.p encoding), chart PNGs

40+ canonical shortcuts wired: Ctrl+1 (Format Cells), Shift+F8 (Add to Selection), Ctrl+Shift+L (AutoFilter), Ctrl+Alt+L (re-apply filter), Alt+= (AutoSum), F9 (recalculate), Ctrl+W (close), Alt+F1 (chart), Ctrl+E (Flash Fill), Ctrl+F3 (Name Manager), Ctrl+Alt+V (Paste Special), Ctrl+` (Show Formulas), Ctrl+[ / Ctrl+] (precedents / dependents), Ctrl+Shift+D (pivot drill-down), number-format shortcuts, hide/unhide rows/columns, border combos.

Available in the Docker image. Single-user on the hosted demo.

• Share dialog — File → Share for co-editing. Set a password, choose edit or view-only, get two copyable URLs
• Presence avatars — title-bar avatar stack with "Active now / Last seen Ns ago" tooltips; idle peers fade
• Live cursors — each peer's selection range in their color, with a name label, tracking scroll and frozen panes
• Live-typing ghost — characters appear in the peer's cell as they type, not just on commit
• Full mutation sync — cell values, styles, structure, conditional formatting, data validation, drawings, workbook metadata (tab colors, zoom, freeze, sheet visibility) all propagate cross-peer
• View-only enforcement at the Univer engine layer — view-only joiners cannot mutate the workbook, not just at the UI level
• Session-history panel — per-room op log with timestamps; review or revert any change
• Divergence detection — amber "Out of sync" pill when state vectors diverge; "Waiting to reconnect" banner on WebSocket drop
• Password-protected rooms — SHA-256 + constant-time compare; wrong password → HTTP 401 on the WS upgrade
• Op-log compaction — long-lived rooms compact the Yjs update log on requestIdleCallback to keep memory bounded
• Joiner fast-path — gzip-streamed pre-parsed snapshot from the server; joiners skip the xlsx parse entirely

See docs/CO-EDITING.md for the full architecture.

• Your data stays on your server. No third-party calls, no telemetry, no Google / Microsoft account required. Files live in your container / volume (or Redis when persistence is on).
• Co-editing rooms are password-gated: SHA-256 hashing with a constant-time compare; a wrong password fails the WebSocket upgrade with HTTP 401 (never a partial join).
• View-only is enforced at the Univer engine layer, not just the UI — view-only joiners physically cannot mutate the workbook.
• Personal mode (multi-user) uses a bcrypt users table (SQLite) with per-user file scoping and an admin panel — see docs/self-hosting/personal-mode.md.
• WOPI mode verifies host JWT tokens and honours Lock/Unlock + token refresh — see docs/STORAGE_MODES.md.
• Apache-2.0, fully auditable; built only on Univer OSS (never the closed Pro package).

A single multi-arch image (linux/amd64 + linux/arm64). Web, Hocuspocus, and Fastify run in one container; Redis runs alongside for room persistence.

docker run --rm -p 3000:3000 casualoffice/sheets:latest

Open http://localhost:3000. Anonymous mode — no signup, no persistence; close the container and everything's gone. Good for kicking the tyres.

Paste this docker-compose.yml and run docker compose up -d:

services:
  app:
    image: casualoffice/sheets:latest
    restart: unless-stopped
    ports: ['3000:3000']
    volumes:
      - casual-data:/data
    environment:
      # Phase C — sign up, save, reopen across restarts.
      CASUAL_STORAGE: local
      CASUAL_LOCAL_PATH: /data
      CASUAL_PERSONAL_MODE: single
      # Y.Doc snapshots for co-edit rooms.
      REDIS_URL: redis://redis:6379
      ROOM_TTL_MIN: '60'
    depends_on:
      redis:
        condition: service_healthy

  redis:
    image: redis:7.4-alpine
    restart: unless-stopped
    command: ['redis-server', '--appendonly', 'yes']
    volumes:
      - redis-data:/data
    healthcheck:
      test: ['CMD', 'redis-cli', 'ping']
      interval: 10s
      timeout: 3s
      retries: 5

volumes:
  casual-data:
  redis-data:

Open http://localhost:3000, sign up — your account + workbooks live in the casual-data volume and survive docker compose down. CASUAL_PERSONAL_MODE=multi keeps signup open if you want more than one account on the same instance; none reverts to the anonymous shape.

For an admin without manual signup, set CASUAL_BOOTSTRAP_USER=admin:hunter2 once in your .env — silently no-ops after the users table has a row. Full reference: docs/ENV.md, docs/self-hosting/personal-mode.md.

1. Open http://localhost:3000. File → Share for co-editing… to set a password and get two share URLs.
2. Paste either URL into another browser or device — the joiner connects in under a second.
3. Move your selection — peers see your named cursor follow it. Type in a cell — peers see characters appear live.

Copy .env.example to .env; docker compose up picks it up automatically.

VITE_* vars are baked in at build time. Pass them with --build-arg on docker build, or via the args: block in docker-compose.yml.

The full env-var matrix (storage backends, networking, admin, JWT, webhooks, more) is documented in docs/ENV.md — that's the canonical reference the admin panel reads from too.

The editor ships as an npm package — @casualoffice/sheets@0.9.0 — that you mount as a single React component. The SDK stores nothing; it hands you the data on save/exit and you persist it. Collaboration is opt-in; no backend to embed.

Early 0.x, still evolving. @casualoffice/sheets is the new Excalidraw-model editor SDK; the restructure continues (Office chrome slots + storage/collab adapters are still landing). The older @schnsrw/casual-sheets is a pre-restructure line without this API — install @casualoffice/sheets.

import { CasualSheets } from '@casualoffice/sheets/sheets';
import '@casualoffice/sheets/styles';

<CasualSheets initialData={snapshot} onChange={(snap) => persist(snap)} />;

Full guide — install, props, CasualSheetsAPI, xlsx import, opt-in collab: docs/INTEGRATION.md. Sandboxed <iframe> / signed embeds: docs/SDK_SIGNING_EMBED.md.

The admin panel at /admin is the runtime UI for everything above — branding, storage backend selection, networking, room limits, auth providers (JWT live; OIDC + SAML stubbed for v0.2), webhook subscriptions, base path. Enable it by setting CASUAL_ADMIN_USERNAME + CASUAL_ADMIN_PASSWORD + CASUAL_JWT_SECRET on the container.

Prerequisites: Node ≥ 18.17, pnpm 10+

pnpm install               # install workspace dependencies
pnpm dev:web               # Vite dev server  →  http://127.0.0.1:5273
pnpm dev:server            # Fastify + Hocuspocus  →  http://127.0.0.1:3000
pnpm test:e2e              # run Playwright suite (auto-starts web dev server)
pnpm test:e2e:ui           # Playwright UI mode
pnpm lint                  # ESLint
pnpm format                # Prettier --write
pnpm typecheck             # tsc across all packages

Co-editing in dev requires both servers running. Add to apps/web/.env.local:

VITE_COLLAB_WS_URL=ws://127.0.0.1:3000/yjs

Then open http://127.0.0.1:5273/r/<any-room-id> in two tabs.

.
├── apps/
│   ├── web/                     # Vite + React frontend
│   │   └── src/
│   │       ├── collab/          # Yjs bridge, presence, share dialog
│   │       ├── shell/           # title bar, ribbon, menu bar, dialogs
│   │       ├── univer/          # Univer plugin registration + lazy loader
│   │       └── xlsx/            # worker-side import/export (ExcelJS)
│   └── server/                  # Fastify + Hocuspocus (rooms, seed, snapshot)
├── tests/e2e/                   # Playwright e2e suite — 357 tests across 87 files
├── docs/
│   ├── ARCHITECTURE.md          # system design
│   ├── CO-EDITING.md            # op-log + presence design
│   ├── LARGE_FILE_PIPELINE.md   # staged perf plan
│   └── RESEARCH.md              # Univer technical brief
├── vendor/univer-revamp/        # our Univer fork (v0.25.0 submodule, wired via pnpm.overrides)
├── Dockerfile                   # multi-stage build (deps → build-web → runtime)
├── docker-compose.yml           # app + Redis
├── PLAN.md                      # phased build plan
└── CLAUDE.md                    # project guardrails for AI-assisted development

Bootstrap the fork on a fresh checkout (full clone — depth-1 won't carry the history needed for fork commits):

git clone git@github.com:CasualOffice/univer-revamp.git vendor/univer

• No AI / LLM features — the Univer command bus is extensible; wire your own model in later. We're an editor, not an AI product.
• No Univer Pro — everything is built on OSS. Missing features are built here or deferred; the commercial Pro package is never used.
• No native mobile apps — desktop browsers are first-class; mobile back-port (viewer + light editor) ships at ≤ 480 px but isn't a native iOS / Android app.
• No 1:1 Google-Sheets feature parity — we don't chase every Power Query / LAMBDA / niche function. The bar is "the surface a typical business spreadsheet uses, round-tripped honestly."

Apache-2.0. See LICENSE and NOTICE.

Our fork of Univer (vendor/univer/ → CasualOffice/univer-revamp) retains its upstream Apache-2.0 license. It is gitignored from this repo and is not part of this project's build today; modifications land in the fork repo independently. See docs/UNIVER_FORK_PERF.md for the active perf-improvement plan.