Rowsmith test data MCP server

rowsmith-mcp

Seeded test data that does not change when you upgrade: pin the output version, and Rowsmith returns the same bytes for the same request and seed for as long as the service runs, checked by a golden test on every build. Fake test data from a schema, reproducible by seed. Free, no key. CSV, JSON or SQL, plus an MCP server for your agent.

curl -s https://testdata-api.re-jam620.workers.dev/v1/generate -H 'content-type: application/json' \
  -d '{"rows":20,"seed":42,"format":"csv","columns":[{"name":"order_id","type":"sequence","prefix":"ord_","pad":4},{"name":"email","type":"email"},{"name":"total_usd","type":"decimal","min":1,"max":500}]}'

First lines of the output (20 rows):

order_id,email,total_usd
ord_0001,amara.weber561@mail.test,230.25
ord_0002,maya.wang873@mail.test,17.04

Works in: pytest, Playwright, dbt, Postgres

Comparing tools? Rowsmith, Faker or Mockaroo: which to use

An MCP server for Rowsmith: fake test data (CSV, JSON or SQL INSERTs) generated from a table schema. It is a thin client of the public Rowsmith API, free and rate-limited.

Quickstart (60 seconds)

1. Add Rowsmith to Claude Desktop, Cursor or another MCP client:

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

1. Ask: "Generate 20 orders with a fixed seed as CSV"
2. Or call the API directly:

curl -s https://testdata-api.re-jam620.workers.dev/v1/generate -H 'content-type: application/json' \
     -d '{"rows":20,"seed":42,"format":"csv","columns":[{"name":"order_id","type":"sequence","prefix":"ord_","pad":4},{"name":"email","type":"email"},{"name":"total_usd","type":"decimal","min":1,"max":500}]}'
   curl -s 'https://testdata-api.re-jam620.workers.dev/v1/invalid?kind=email&count=5&seed=42'
   ID=$(curl -s https://testdata-api.re-jam620.workers.dev/v1/sandbox -H 'content-type: application/json' -d '{"seed":42}' | sed -E 's/.*"id":"([^"]+)".*/\1/')
   curl -s https://testdata-api.re-jam620.workers.dev/v1/sandbox/$ID/charges -H 'content-type: application/json' \
     -d '{"amount":1999,"currency":"usd","card":"4242424242424242"}'

Python's standard-library urllib is blocked by Cloudflare before it reaches the API (403, error code 1010) when it sends its default User-Agent. Set your own, e.g. User-Agent: my-tests/1.0. In our tests on 2026-10-18, requests, httpx, aiohttp, Node and curl worked with their defaults.

Shortened. The full README is on GitHub.