Schemity is database design software for software engineers. It turns your live database into a local architecture map, lets you review every schema change - yours or your AI agent’s - with lint, dependency impact, and the exact migration SQL before it is applied, and then helps you design the next one. It runs on your machine as a desktop app for macOS, Windows, and Linux, stores every diagram as plain JSON in a folder you choose, and is a one-time purchase with no subscription.
What does Schemity do?
Three things, in the order you usually need them:
- Understand your schema. Connect PostgreSQL, MySQL, MariaDB, SQL Server, or SQLite and Schemity draws every table at once, including the foreign keys the database never declared, inferred from column names. Group tables into context views, one per domain, and the Context Map shows how those domains depend on each other, counting the real foreign keys behind every arrow.
- See the impact of every change. Edit the diagram and Schemity generates the migration SQL. Before it runs, impact analysis reports lost rows, statements that will fail on existing data, table rewrites, and dependent views, and schema lint marks design problems on the diagram itself. A migration file written by Prisma, Alembic, Flyway, or by hand gets the same impact analysis without being executed. It reads the database, not your application: an ORM query that breaks is your test suite’s job.
- Design the next one. Draw entities and relationships, with junction tables created for you, or start from imported SQL or DBML. A diagram does not need a database behind it at all.
How does Schemity work with AI agents?
Schemity is a local database MCP server, so Claude Code, Cursor, Codex, or any MCP host can read your schema, context views, dependencies, lint findings, and the cost of pending changes. You and the agent work on the same diagram as equal users, with one difference: only you can change the database.
- The agent never holds database credentials. It reads the schema through Schemity.
- Its edits are staged on the open diagram. Every step is in History, one undo away, and nothing is saved until you save.
- A migration it writes in your codebase is drawn as a change preview before anything runs.
- Nothing is written to the database until you click Migrate. On a Production connection, you type the database name first.
A typical first session: connect a legacy database, ask your agent in the codebase to group the tables by domain, review what it did, then open the Context Map to read the module dependencies.
Where does my schema go?
Nowhere you did not send it. Schemity has no vendor cloud: the connection runs from your machine straight to your database, passwords live in your operating system’s keychain, and diagrams are JSON files you version in Git and review in pull requests like the rest of your code. That is why it fits client and NDA work, IT-restricted environments, and air-gapped machines.
When you use an AI agent, Schemity passes the schema to it, so the schema goes wherever that agent already sends your code. With a local model, that is nowhere at all.
Who is Schemity for?
Software engineers and consultants who design and change real databases:
- Teams working with AI agents who want the agent to understand the database without handing it a connection string.
- Engineers inheriting a legacy database who need to see its domains and dependencies before changing it.
- Anyone changing production who wants to know what a migration will do before it runs.
- Client and NDA work where schemas cannot leave the building.
Does Schemity run on desktop or in the browser?
Both. The desktop app does everything on this page. Schemity Lite is a free browser version for designing schemas, with cloud save, public share links, and export to SQL, DBML, Mermaid, and images. Live database connections, impact analysis, lint, context views, the MCP server, and migrations are desktop features, unlocked by a one-time license after a two-week trial with every feature on. Diagrams move between the two as JSON files.
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.