Praetorium

Build a Warhammer 40,000 army list. Track the battle live from each player's phone.

praetorium.gg

Product

Praetorium is free and open source. It supports games between up to four friends: 1v1, 2v1, or 2v2 Doubles. Every instance also seats practice opponents, so you can play a full battle through on your own. The home page shows the battles being played right now, so there is something to watch before there is something to play.

Players can:

• Build, import, save, share, print, and export army lists.
• Run public or private league events with approved entry, sealed roster submission, organizer-controlled reveal, and reusable event history.
• Follow live or finished battles with their frozen rosters and battle history, without taking a seat.
• Choose who can watch their battles: anyone, their friends, or only the players at the table.
• Watch the battles being played now from the home page, or read back through finished ones.
• Use faction, detachment, unit, loadout, enhancement, and points data from community catalogues.
• Configure missions, deployment, terrain, formations, stratagems, and mission cards.
• Track rounds, phases, command points, victory points, and each unit's models, wounds and losses.
• Review and correct a finished battle without deleting its history.

The app stores one append-only command log for each battle. It derives the current state from that log. The server validates every command before it appends it.

Scope

Praetorium does not provide matchmaking, chat, rankings, standings, or tournament pairings, nor a rules encyclopedia. An account is required to play, though not to watch a public battle.

This repository contains no game data. Each instance downloads verified snapshots from the configured community sources.

Use

praetorium.gg is the supported service. It includes catalogue updates and persistent storage.

Self-hosting is available for experienced operators. See Self-hosting.

Development

Development requires Node 24.x, pnpm 11.15.0, and just 1.58.0.

just install
just catalogue-sync
just dev

Run just check before you submit a change. Read CONTRIBUTING.md for setup and test details. Read AGENTS.md for architecture rules.

Architecture

• src/core contains the IO-free battle, catalogue, and roster domain.
• src/db contains the Postgres schema and Drizzle repository.
• src/server contains authentication, application services, catalogue loading, and server functions.
• src/client contains React components, hooks, and queries.
• src/routes contains thin TanStack Router route files.

Data and trademarks

Catalogue definitions come from BSData. Rules data comes from 40kdc-data under CC BY 4.0. See catalogue/README.md for all sources and licenses.

Warhammer 40,000 and related marks belong to Games Workshop. Praetorium is unofficial and is not endorsed by Games Workshop.

Praetorium is licensed under the GNU Affero General Public License v3.0.