Schemity is an offline ERD tool for software engineers. It runs on your machine as a desktop application, stores every diagram as plain JSON on disk, and never sends your schema to a server. If you have ever wanted a database design tool that respects an NDA, passes an IT security review, and works on an air-gapped laptop, this is it.
The core idea
Most ERD tools are cloud apps. Your schema - often the most sensitive description of a product you have - lives on someone else’s servers behind a login. Schemity inverts that. It is a local ERD tool with no cloud dependency: your data model is a file on disk that you own, version, and back up like any other source code.
Who it is for
Schemity is built for engineers and consultants who design real databases under real constraints:
- Client and NDA work where schemas cannot leave the building.
- Air-gapped or IT-restricted environments where cloud tools are blocked.
- Git-native teams who want their data model reviewed in pull requests like the rest of the codebase.
What makes it different
- Offline first - every feature works with the network cable unplugged.
- JSON storage - diagrams are human-readable files, not an opaque binary blob.
- Git-native - diff and review your schema changes alongside your code.
- One-time purchase - a lightweight desktop ERD tool you buy once, not a subscription.
- BYOK AI - optional AI assistance using your own provider API key, so even AI-assisted design stays private.
Desktop and web
Schemity ships as a desktop app for macOS, Windows, and Linux. There is also a free web version that runs fully in your browser for offline design. Connecting to live databases, importing SQL, AI chat, and generating migrations are unlocked by a one-time desktop license.
Where to go next
If this is your first time, head to Install & First Launch to get set up, then Create a Workspace to start your first project.