SessionZero is a free and open-source TTRPG "companion" application for managing characters, templates, data, and game sessions. It allows you to utilize any TTRPG system by being completely data-driven with user-generated content.
+SessionZero is built to be a flexible, minimal companion for any tabletop RPG system you want to run—from popular games to niche homebrew. It’s designed to get out of your way and put you in total control of your game data.
+ +We believe your data should always be yours. That’s why SessionZero is built around three core principles: it's system-agnostic, offline-first, and truly open source (AGPL-3.0).
-Features
+The Core of SessionZero
Offline-First, No Strings Attached
-By default, SessionZero works completely offline. Your data is stored locally on your machine. No account required. No phoning home. You have total ownership over your data.
+System-Agnostic Datapacks
+The entire application is driven by Datapacks (.szp files). These are structured archives of JSON files and assets that define a game system’s rules, character sheets (Templates), and content (Datasets like items and monsters). If you can define it, you can play it.
Build Your Own Universe
-You're the architect. Create templates for character sheets, define custom stats, and build your own collections (Datasets) of items, spells, monsters, or anything else your game needs. All data is stored in a human-readable format (SZF) that you can easily export, share, and back up.
+Offline-First & Self-Hostable
+SessionZero works fully offline by default, storing all your content and characters locally on your device. For shared, real-time play with friends, you have the option to run your own server instance. This means no central service is required, and your data ownership remains absolute.
Run Your Game, Your Way
-Use SessionZero for your private, offline session notes, or host a live online game for your friends. As a Game Master, you can manage NPCs, track turns, and make real-time updates to character sheets. Players can join with their own characters and keep private session journals.
+Shared Sessions and Live Play
+For Game Masters, Sessions allow you to track initiative, manage NPCs, and make real-time updates to player characters. Players can join your game, keep private journals, and reference the campaign's required Datasets. When online, updates are pushed instantly via WebSockets.
Open Source and Transparent
-SessionZero is open-source software. We believe in the right to see what's going on behind the scenes and contribute to the project. No AI chatbots, no ads, no bloat. We promise.
+The code is licensed under AGPL-3.0. You're free to inspect, modify, and contribute to the project. There's no telemetry, no lock-in, and no hidden features—just community-driven TTRPG software built for TTRPG players.
The SessionZeroDB
+SessionZeroDB
-SessionZero includes access to the SessionZeroDB, a free online repository of user-created templates and datasets. When online, the application can automatically find and download required content for you.
+Every server instance includes a SessionZeroDB where users can download and share custom datapcks.
-Who Is This For?
+Federation (Future Plan - Phase 2)
+ +The future plan is Federation: allowing independent SessionZero servers to discover and share public content (Datapacks, Templates) across any SessionZero server instance that is configured to allow public discovery. This enables players on one self-hosted server to connect with and use content from another public server they trust, without relying on a central authority.
+ +Who Should Use This?
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- Players who want total control over their character sheets and game data -
- Game Masters who want to run any system whether it's a popular RPG, niche indie game, or their own homebrew content -
- Anyone who's tired of apps that feel bloated, hard to learn, restrictive, or designed to constantly sell you something +
- Players and GMs who demand total control over their character sheets, notes, and game data. +
- Anyone tired of apps that are bloated, restrictive, or constantly designed to sell you content. +
- Developers or tinkerers who want a flexible, open-source platform to build their own TTRPG tools.
Why use Godot?
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- - Godot Engine's editor is that it itself is made with Godot. This proves that it can be used to make flexible desktop applications, while providing game engine features like networking and an easy to use UI system. - -
- - Godot is FOSS (Free and Open Source Software) as well, which aligns with our core values. - -
- - It is easy to learn and use, which allows for anyone to modify the application to their liking, creating "mods/plugins" and making SessionZero work for them. - -
The Bottom Line
- -SessionZero is about freedom, flexibility, and community.