A free, open-source character sheet manager for Old-School Essentials and the broader OSR community.
OSE Sheets is a web application for managing characters, campaigns, and party inventory in OSE games — particularly useful for online play. GMs create campaigns, players join with invite codes, and everyone gets live, interactive character sheets with 3D dice rolling, spell tracking, and automated combat math.
This is a community project. Free to use, free to host, free to hack on. If you play OSE or any B/X-derived game, this is for you.
- Full OSE stats, saving throws, attribute modifiers, and THAC0
- Class system with auto-populated saves, THAC0, spell slots, and class skills from templates
- 3D dice rolling — click any stat, attack roll, or damage roll to throw dice on screen
- XP tracking with GM-awarded XP and level-up with automatic stat recalculation
- Print-friendly character sheet view
- Spellbook management for arcane casters, divine casters get full spell access
- Daily memorization with slot tracking per spell level
- Cast/rest cycle — mark spells as cast, rest to restore all slots
- Equip/unequip weapons and armor with auto-computed AC (including rear AC, shieldless AC)
- Weapon table with THAC0, damage, range, and special attack qualities
- Ammo tracking with auto-decrement on ranged attack rolls
- Item abilities — rings, wondrous items, and gear can grant attribute modifiers, skill rolls, auras, round effects, and special attacks
- Revealable item secrets — GMs attach hidden information and reveal it piece by piece as players identify things in-game
- Currency tracking (cp, sp, ep, gp, pp) with save to character
- Hire retainers as sub-characters linked to a PC master
- CHA-based limits on max retainers and base loyalty
- Loyalty checks via 2d6 dice roll
- Dismiss retainers to make them independent characters
- 12 OSE mercenary types (archers, footmen, horsemen, crossbowmen, longbowmen, peasants, wolf riders) with per-race costs
- Hire/dismiss controls with quantity adjustment
- Wartime toggle doubles all costs
- Morale checks via 2d6 dice roll
- Payday button deducts monthly wages from character wealth
- GMs create campaigns, players join via invite code
- Permission system — GMs see everything; players see their own sheets and what the GM reveals
- Party stash — shared loot pool that characters can take from or return to
- Encounter tracker — initiative tracking, round management, HP adjustment, condition tracking with turn counters
- Combat table — unified view of PCs, retainers, and monsters with clickable THAC0/damage/morale rolls
- Monster bestiary — full CRUD for campaign-specific and default monsters with stat blocks
- Dungeon time tracker — turn-by-turn tracking with torch/lantern life, ration consumption, custom timers, and event history
- Database backup and restore (server-side and file upload)
- Default content seeding — classes, items, spells from OSE rules
| Layer | Tech |
|---|---|
| Frontend | SvelteKit 2, Svelte 5, Tailwind CSS 3 |
| Backend | FastAPI, SQLAlchemy 2, Alembic |
| Database | SQLite (trivially swappable to PostgreSQL) |
| Auth | Google OAuth 2.0, JWT tokens |
| Dice | dice-box 3D physics engine |
- Python 3.11+
- Node.js 18+
- A Google Cloud OAuth client (for authentication)
# Clone
git clone https://github.com/morduun/ose-sheet.git
cd ose-sheet
# Install everything
make install
# Set up the database
make migrate
# Seed default content (classes, items, spells)
make seed-all
# Configure OAuth (see backend/.env.example)
cp backend/.env.example backend/.env
# Edit backend/.env with your Google OAuth credentials# In one terminal — backend API on :8000
make backend
# In another terminal — frontend on :5173
make frontendVisit http://localhost:5173 to start playing.
For local development without Google OAuth, you can generate a token directly:
curl -X POST http://localhost:8000/api/auth/token \
-H "Content-Type: application/json" \
-d '{"email": "admin@example.com"}'| Command | Description |
|---|---|
make install |
Install backend + frontend dependencies |
make backend |
Start the API server with hot reload |
make frontend |
Start the frontend dev server |
make dev |
Start both backend and frontend |
make migrate |
Apply database migrations |
make migrate-new |
Create a new migration |
make seed-all |
Seed test user, admin, classes, items, and spells |
make build |
Production build of the frontend |
make backup |
Create a database backup |
make restore FILE=<path> |
Restore from a backup file |
make list-backups |
List available backups |
make db-shell |
Open a SQLite shell to the database |
ose-sheet/
├── backend/
│ ├── app/
│ │ ├── api/ # FastAPI route handlers
│ │ ├── models/ # SQLAlchemy ORM models
│ │ ├── schemas/ # Pydantic request/response schemas
│ │ └── services/ # Business logic (auth, permissions, modifiers)
│ ├── alembic/ # Database migrations
│ ├── seed_data/ # Default classes, items, spells as JSON
│ └── requirements.txt
├── frontend/
│ ├── src/
│ │ ├── lib/
│ │ │ └── components/ # Svelte components (sheet, items, classes, shared)
│ │ └── routes/ # SvelteKit file-based routing
│ └── package.json
├── reference/ # OSE PDFs and screenshots
├── Makefile
└── docs/
This is an open project under the MIT license. Contributions are welcome — whether that's adding new character classes, fixing bugs, improving the UI, or adding features.
The default content covers the four core B/X classes (Fighter, Cleric, Magic-User, Thief). Adding the demi-human classes (Dwarf, Elf, Halfling) or OSE Advanced classes (Druid, Illusionist, Paladin, Ranger, etc.) is as simple as adding a JSON file to backend/seed_data/character_classes/ or creating a new class using the Referee UI.
This project is not affiliated with or endorsed by Necrotic Gnome. Old-School Essentials is a trademark of Necrotic Gnome. Game mechanics are used under the terms of the Open Game License.