Design ER diagrams, define tables and relationships manually or via prompts, and share via URL.
- Visual canvas - drag-and-drop tables on an interactive grid with zoom, pan, and fit-to-view
- Tables & columns - create tables with default columns (id, created_at, updated_at); add columns with types (VARCHAR, INTEGER, BOOLEAN, TEXT, TIMESTAMP) and constraints (PRIMARY KEY, NOT NULL, UNIQUE)
- Relationships - connect columns visually to define one-to-one, one-to-many, and many-to-many relationships
- Junction tables - auto-generate junction tables with foreign keys for many-to-many relationships
- AI-powered design - create tables, columns, and relationships using natural language; includes batch operations, smart auto-layout, and LLM safety features
- SQL export/import - export schemas as SQL DDL or import from SQL dumps with dialect selection (PostgreSQL, MySQL, SQLite)
- JSON export/import - download or load schemas as JSON files for backup and transfer
- Load schemas - open previously saved schemas from local storage
- Share via URL - generate compressed shareable links with the full schema embedded in the URL hash
- Auto-save - changes are automatically saved to localStorage after 1 second of inactivity
- Restore on startup - automatically loads the last opened schema when you return
- Undo/redo - full undo history for schema changes (Ctrl+Z / Ctrl+Shift+Z)
- Validation - validate schemas for errors and warnings
- Dark mode - toggle between light and dark themes, persisted across sessions
- PWA - installable as a standalone app with offline support via service worker
- React 19 + TypeScript 5.9
- Vite 8 (build tool)
- Hono + AI SDK for AI-powered schema design API
- node-sql-parser for SQL parsing
- React Flow (@xyflow/react) for the interactive canvas
- Dagre for auto-layout
- Zustand + Zundo for state management and undo/redo
- Tailwind CSS 4 + shadcn/ui + Radix UI for styling and components
- Lucide for icons
- LZ-String for URL compression
- vite-plugin-pwa + Workbox for PWA support
- Vitest for testing
pnpm install
pnpm dev| Command | Description |
|---|---|
pnpm dev |
Start dev server |
pnpm dev:api |
Start AI API server (requires API keys; see .env.sample) |
pnpm build |
Type-check and build for production |
pnpm preview |
Preview production build locally |
pnpm test |
Run tests |
pnpm test:watch |
Run tests in watch mode |
pnpm lint |
Lint with ESLint |
pnpm format |
Format with Prettier |
pnpm typecheck |
Type-check without emitting |
pnpm check |
Run typecheck, lint, and tests |
The app includes an AI API (Hono + AI SDK) for natural language schema generation, but has no backend database. All schema data lives in the browser.
- Schemas are stored in
localStorageunder the keyermate:schemas - Active schema ID is stored under
ermate:activeSchemaId - Theme preference is stored under
ermate:theme - Shared schemas are encoded in the URL hash (
#schema=...) using LZ-String compression - PWA cache is managed by Workbox for offline access