ChartDB Schema Designer: Draft a Database Locally

ChartDB Local Schema Designer is a local app for sketching a database before you build it. You add tables and columns, set types and constraints, draw the relationships between tables, and see the whole schema as a diagram. It's based on ChartDB, the open-source database diagram editor, scoped down to drafting a new schema and exporting it as JSON.

What it does

Designing tables in your head, or in a spreadsheet, is how you end up with a column you need in the wrong table three months later. A diagram shows the relationships before you've committed to them.

Add tables and columns. Build out each table with its columns.

Set types and constraints. Change column types and constraints as the design firms up — which fields are required, which are unique, which are keys.

Draw relationships. Connect tables to show how they relate, like each order belonging to one customer. This is the entity–relationship thinking that most database design starts from.

See the diagram. View the whole database schema at once, which is where missing links and duplicated data become obvious.

Save or export as JSON. Keep the design locally, or export it as JSON to import again later.

What it won't do

• connect to a live database or read an existing one
• generate SQL scripts to create the tables
• create, change, or migrate anything in a real database

It's a drafting tool. Turning the design into actual tables — the data definition language statements, such as CREATE TABLE — is a separate step, done by you or by the tools your project already uses.

When to reach for it

• You're starting a new app and want to settle the data model first
• You need to explain a proposed schema to a teammate or a client
• You're adding a feature and want to see where new tables fit
• You're learning database design and want to practise on a diagram
• You don't want to connect a design tool to a real database

How it differs from ChartDB

ChartDB is built around visualizing databases you already have. The Taku version is built around drafting new ones.

If you want a diagram of a database that already exists, or SQL to create one, use ChartDB itself. If you want a quiet place to design a new schema before any database exists, the local designer is enough.

What's actually inside

One app. It runs locally, with no database connection, no API key, and no network requests. Your design stays in the files you save.

Setting it up

The GitHub route (the original). ChartDB has a cloud version that needs no account. To run it yourself, the README gives npm install and npm run dev, or a Docker image. The AI export features need an OpenAI API key or a custom inference endpoint configured at build or run time, and the project includes privacy-focused analytics you can switch off with a flag.

The Taku route. Open ChartDB Local Schema Designer in Taku and add your first table.

Who made it

ChartDB is an open-source project from the ChartDB team, released under the GNU AGPL 3 license. The Taku version was published to the Taku marketplace by Ricky.

If you're not the database person

You don't need to understand GitHub, Codex, or Claude Code to sketch a database. Diagram tools that connect to live databases assume you have credentials, a running database, and the comfort to point a tool at it.

Taku is a desktop workspace built for skipping that: find something someone already built, open it in your own workspace, and use it. Browse the free app library for more developer tools, or read about AI database generators for tools that go further and build the database for you. Once a schema exists, Schema-Grounded SQL Queries writes queries against it from plain English.

Download Taku and draft your next schema. Taku is in Beta, and the Mac app is available now; there's also an experimental, unsigned Windows build for Windows 10 and 11.

FAQ

What does ChartDB Local Schema Designer do?

It lets you add tables and columns, set column types and constraints, draw relationships, view the schema as a diagram, and save it locally or export it as JSON.

Can it connect to my database?

No. It doesn't connect to or read any database. The original ChartDB imports an existing schema by running a query you paste into your database.

Can it generate SQL?

No. It exports JSON. ChartDB itself can export SQL scripts, including AI-assisted scripts for other databases.

Do I need an OpenAI key?

No. The local designer has no AI features. The original ChartDB needs a key or a custom endpoint only for its AI export.

Is it free?

The app is free in the marketplace. For what Taku itself costs, see pricing.

Key points

• Drafts a database schema: tables, columns, types, constraints, and relationships.
• Shows the whole schema as a diagram, and exports it as JSON.
• No database connection, no SQL generation, no AI, no network.
• Based on ChartDB, which visualizes existing databases and exports SQL.
• Use ChartDB for existing databases; use the local designer for new ones.