SessionZero is built to be a flexible companion for any tabletop RPG system you want to run, whether that's a popular game or your own homebrew creation. The goal is simple: give you full control over your game data without getting in your way.
Your data should always belong to you. SessionZero is built around three principles: it works with any game system, it runs offline on your own device, and it's completely open source under the AGPL-3.0 license.
How SessionZero Works
Works With Any Game System
SessionZero uses something called Datapacks, which are basically packages that contain everything needed to play a specific game system, or just simply additional content that can be used anywhere. Think of them like expansion packs, but for the rules and content of your game. A Datapack includes things like character sheet templates, session templates, items, monsters, and whatever else the game needs. You can download Datapacks others have made, or create your own for any system you want to play.
Runs Offline on Your Device
Everything lives on your device by default. Your characters, your notes, your campaigns, all stored locally. If you want to run a live game with friends online, you have two options: set up your own self-hosted server, or join an already established server that someone else is running. There's no company-run service in the middle, which means you're not dependent on anyone else to keep your games running.
Live Sessions With Your Group
When you're running a game, SessionZero helps you manage the session. Game Masters can track turn order, control NPCs, and update player information in real time. Players joining your game can keep their own private notes, view shared campaign information, and see updates as they happen. There's also a chat feature for quick communication during play.
Open Source and Community-Driven
The entire project is open source, which means anyone can look at the code, suggest changes, or build their own version. There's no tracking, no premium features locked behind paywalls, and no corporate interests. It's built by and for TTRPG lovers.
Sharing Custom Content
Every server has a built-in library called SessionZeroDB where people can share the Datapacks they've created. If someone makes a great character sheet template or a collection of homebrew items, they can upload it for others to download and use in their own games.
Future Plans: Federation
Down the road, we're planning to add federation support. This would let different SessionZero servers talk to each other and share public content, similar to how email works across different providers. If you're running your own server, you could pull in content from other servers you trust, or even let players from different servers join the same game session. It's all optional and there's still no central authority required.
Who This Is For
- Players and GMs who want complete control over their character sheets, notes, and game data.
- Anyone frustrated with apps that are bloated, restrictive, or constantly trying to sell you something.
- People who prefer tools that respect their privacy and don't require an internet connection.
- Developers or hobbyists interested in tinkering with an open platform for tabletop gaming.
What SessionZero is NOT
SessionZero is not a replacement for your official rulebooks or published modules. It's a companion tool for managing characters and sessions using content you create or source yourself. There's no monetization of user content, no digital storefront, and no official content sales by design. SessionZero's objective is helping you organize and play the games you already own or create yourself.