SeedWeaver

Generate realistic, referentially-coherent test data from your real database schema — straight from Claude, Cursor, or any MCP client.

Paste your CREATE TABLE SQL (or a JSON schema) and SeedWeaver generates seed data where foreign keys actually resolve to real primary keys, unique constraints are respected, and values are realistic (names, emails, dates, decimals). Unlike generic mock-data tools that spit out statistically random junk, SeedWeaver understands the relationships in your schema.

Ask your AI: "Generate 50 users and 200 orders for this schema" — and get INSERTs you can run immediately, with every order.user_id pointing at a user that exists.

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Why SeedWeaver

Most "fake data" tools (Faker wrappers, random generators) give you isolated rows with no awareness of your schema. The moment you have foreign keys, you're back to hand-wiring relationships. SeedWeaver:

• Resolves foreign keys — referenced tables are generated first (topological ordering), and FK columns point at real generated keys.
• Respects constraints — unique columns stay unique, primary keys are unique, NOT NULL is honored.
• Reads your real schema — paste Postgres/MySQL CREATE TABLE DDL directly, no manual config.
• Realistic values — names, emails, addresses, companies, dates, decimals, enums.
• Outputs what you need — SQL INSERT statements, JSON, or CSV.

Install

npx -y seedweaver-mcp

Add to your MCP client config (Claude Desktop / Cursor / Windsurf):

{
  "mcpServers": {
    "seedweaver": {
      "command": "npx",
      "args": ["-y", "seedweaver-mcp"]
    }
  }
}

Tools

Tool	What it does
analyze_schema	Parse a schema (SQL DDL or JSON) and report tables, columns, relationships, and generation order. Run this first to confirm SeedWeaver reads your schema correctly.
generate_seed_data	Generate coherent test data. Returns SQL INSERTs (default), JSON, or CSV.

Examples

From SQL DDL:

Generate 20 rows of test data for:

CREATE TABLE users (
  id UUID PRIMARY KEY,
  email VARCHAR(255) UNIQUE NOT NULL,
  full_name VARCHAR(100),
  created_at TIMESTAMP
);
CREATE TABLE orders (
  id SERIAL PRIMARY KEY,
  user_id UUID NOT NULL REFERENCES users(id),
  total DECIMAL(10,2),
  status VARCHAR(20)
);

Every generated orders.user_id will be a real users.id.

From a JSON schema (gives you fine control — enums, ranges, per-table row counts):

{
  "tables": [
    {
      "name": "users",
      "rows": 20,
      "columns": [
        { "name": "id", "type": "uuid", "primaryKey": true },
        { "name": "email", "type": "email", "unique": true },
        { "name": "name", "type": "fullName" }
      ]
    },
    {
      "name": "orders",
      "rows": 80,
      "columns": [
        { "name": "id", "type": "serial", "primaryKey": true },
        { "name": "user_id", "type": "fk", "references": "users.id" },
        { "name": "total", "type": "decimal", "min": 5, "max": 500 },
        { "name": "status", "type": "enum", "values": ["pending", "paid", "shipped"] }
      ]
    }
  ]
}

Supported column types: uuid, serial, int, decimal, boolean, email, fullName, firstName, lastName, username, phone, address, city, country, company, url, word, sentence, paragraph, date, datetime, enum, fk.

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Free vs. Pro

The free tier is fully functional for small schemas. Pro removes the limits and adds the features you need for real projects and CI.

	Free	Pro
Tables per schema	2	Unlimited
Rows per table	50	Unlimited
Output formats	SQL, JSON	+ CSV
Deterministic seeds (reproducible data)	—	✓
Custom locales	—	✓
Use in CI / automation	—	✓

→ Get SeedWeaver Pro — $19/mo

Activate by setting your license key:

{
  "mcpServers": {
    "seedweaver": {
      "command": "npx",
      "args": ["-y", "seedweaver-mcp"],
      "env": { "SEEDWEAVER_LICENSE": "your-key-here" }
    }
  }
}

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License

The SeedWeaver MCP server is MIT licensed and free to run. Pro features are unlocked with a paid license key. Built with the Model Context Protocol.