An AI Game Master for tabletop RPG campaigns — open source, self-hosted, and cheaper than a coffee.
A solo session runs ~$0.28 in API usage. Four players for three hours: ~$0.70. No subscription. No platform fees. Just your Anthropic API key and
docker compose up.
Tavern is a self-hosted, SRD 5.2.1-compatible RPG engine powered by Claude as your Game Master. It handles the rules. Claude handles the story. Play in your browser, on your phone at the table, or in a Discord voice channel with friends.
- 🎲 Full SRD 5e rules engine — combat, spells, conditions, and character progression implemented in code, not in prompts
- 🧠 Claude as Game Master — narrative, NPC behaviour, and world reaction powered by Claude
- 🎭 Two ways to play — browser-based web client or Discord bot with voice support
- 💾 Persistent campaigns — state survives across sessions via PostgreSQL
- 👥 Solo and multiplayer — play alone or with a group in real-time
- 📱 Table mode — shared display on a laptop, each player on their phone
- 💸 Cost-efficient — prompt caching and mixed model routing keep API costs minimal
- 🐳 One-command setup — a single
docker compose upis all it takes - 🌍 Community worlds — import custom world presets or use the included Shattered Coast setting
- Docker and Docker Compose
- An Anthropic API key
git clone https://github.com/t11z/tavern
cd tavern
cp .env.example .env
# Add your ANTHROPIC_API_KEY to .env
# Optionally add DISCORD_BOT_TOKEN for Discord integration
docker compose upOpen http://localhost:3000 and start your adventure.
In your browser: Open the web client, create a campaign, build a character, and play. Solo or invite friends via join code.
At the table: Open the shared display on a laptop or TV. Each player joins on their phone by scanning a QR code. Claude narrates through the speakers.
On Discord: Add the Tavern bot to your server, start a campaign in a text channel, and play — Claude narrates as the GM.
Setup:
- Create a Discord application at discord.com/developers/applications and add a bot user.
- Enable the Message Content privileged intent under Bot → Privileged Gateway Intents.
- Copy the bot token and add it to your
.envfile:DISCORD_BOT_TOKEN=your-token-here - Run
docker compose up— thediscord-botservice starts automatically alongside the API. - Invite the bot to your server using the OAuth2 URL (scopes:
bot,applications.commands; permissions:Send Messages,Manage Threads,Read Message History).
See docs/game-design/discord-bot.md for the full command reference and gameplay guide.
Tavern is a headless game server with a client-agnostic API. The web client and Discord bot are two reference clients — both first-class, both maintained by the core team.
The server separates two concerns:
| Layer | Responsibility |
|---|---|
| Rules Engine | Deterministic SRD logic — dice, combat, spells, conditions |
| Narrator | Claude handles narration, NPC behaviour, world reaction |
Claude never sees raw rulebook text at runtime. It receives a structured state snapshot — character status, scene context, a rolling session summary — and responds as a narrator. The numbers come from your code.
Cost optimisations built in:
- Prompt caching for static context (system prompt, character sheet)
- Haiku for low-complexity responses, Sonnet for narration
- Rolling summary instead of full conversation history
See docs/adr/ for the full set of architecture decision records.
- Backend: Python 3.12+ / FastAPI
- Databases: PostgreSQL 16+ (application data) · MongoDB via 5e-database (SRD data)
- Web Client: React (Vite)
- Discord Bot: Python (discord.py)
- LLM: Anthropic API (provider-abstracted)
- Deployment: Docker Compose
Tavern's game data — spells, monsters, classes, species, equipment, and more — comes from the 5e-bits/5e-database project, a community-maintained SRD 5.2.1 dataset served as a MongoDB container.
No manual import step is required. docker compose up starts the SRD database
alongside everything else. The data is ready to query immediately.
Custom content: GMs can add homebrew monsters, modify SRD creatures, and create custom spells and items through the API. Custom content is reusable across campaigns. Per-campaign overrides let you tweak SRD entries for a specific campaign without affecting others.
Tavern is licensed under the Apache License 2.0.
This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.
This product is 5E compatible.
Contributions welcome. Architecture decisions are documented in docs/adr/. Please read them before proposing changes — accepted ADRs are binding constraints.
See CONTRIBUTING.md for guidelines.
Tavern's SRD data comes from 5e-bits/5e-database.
If you find an error in the SRD data (wrong spell damage, incorrect monster AC, missing class feature):
- Check the 5e-database issues to see if it's already reported.
- If not, open an issue or PR in the 5e-database repository. Fixes there benefit the entire ecosystem, not just Tavern.
- Once the fix is released in a new 5e-database version, we bump the image tag in our
docker-compose.yml.
Custom content contributions (community monsters, homebrew items, world-specific creatures) are welcome. These live in the Instance Library and can be submitted as data files. See the custom content API documentation for the expected document format.