openapi-toolkit

openapi-toolkit is an open-source tool designed to streamline the integration of OpenAPI (formerly known as Swagger) specifications into your development workflow. By taking an OpenAPI/Swagger file as input, the OpenAPI Toolkit automatically generates server and client code, enabling seamless integration of APIs. This automation accelerates development processes, ensures consistency across different platforms, and reduces the risk of manual errors. Whether you're building a new service or integrating with existing APIs, OpenAPI Toolkit simplifies the process by providing ready-to-use code tailored to your OpenAPI specifications.

Generate MCP Server

openapi-toolkit generates a fully functional MCP SDK FastMCP server from any OpenAPI/Swagger spec — one MCP tool per API endpoint, grouped by controller, with the async Pydantic v2 client bundled inline.

Generate

# no install required
npx openapi-toolkit -i https://petstore3.swagger.io/api/v3/openapi.json -g python-mcp-server -t server -o ./my-api-mcp

# or with global install
npm i -g openapi-toolkit
openapi-toolkit -i https://petstore3.swagger.io/api/v3/openapi.json -g python-mcp-server -t server -o ./my-api-mcp

Generated layout:

my-api-mcp/
  pyproject.toml          # uv project: mcp, httpx, pydantic
  README.md
  src/
    mcp_server.py         # FastMCP entry point, tool registration, transport CLI
    client/               # generated async httpx + Pydantic v2 client (inline)
      __init__.py
      client.py
      models/
      controllers/
    server/
      tools/
        <controller>.py   # one file per API controller tag

Install and run

cd my-api-mcp
uv sync
BASE_URL=https://api.example.com uv run python src/mcp_server.py

Transport options

# stdio (default — for Claude Desktop and most MCP clients)
BASE_URL=https://api.example.com uv run python src/mcp_server.py --transport stdio

# SSE
BASE_URL=https://api.example.com uv run python src/mcp_server.py --transport sse --host 0.0.0.0 --port 8000

# Streamable HTTP
BASE_URL=https://api.example.com uv run python src/mcp_server.py --transport streamable-http --host 0.0.0.0 --port 8000 --path /mcp

A fully generated example (Petstore API) is available in this repo: examples/pet-store-mcp

Environment variables

Variable	Description
BASE_URL	Base URL of the target API (required at runtime)
TOOL_FILTER_ROUTES	Comma-separated controller names to load (e.g. pet,store). Loads all if unset.
TOOL_FILTER_METHODS	Comma-separated tool function names to register (e.g. getPetById,addPet). Registers all if unset.

Install

NPM

npm i openapi-toolkit

Auto Generate Client/Server (Cli)

npm i -g openapi-toolkit

# example
openapi-toolkit -i https://petstore3.swagger.io/api/v3/openapi.json -g typescript-axios -o ./src/services/petStore --modelNamePrefix My --modelNameSuffix .dto

# show all options
openapi-toolkit -h

# with docker
docker run --rm --name openapi-toolkit -v "$(pwd)/output:/output" -e CLI_PARAMS="-i https://petstore3.swagger.io/api/v3/openapi.json -g typescript-axios --modelNamePrefix My --modelNameSuffix .dto" barnuri/openapi-toolkit

Auto Generate Client/Server (JS\TS)

const { multipleGenerate, generate } = require('openapi-toolkit');

// use multipleGenerate when you want multiple outputs
(async () => {
    const sharedConfig = { debugLogs: false };
    await multipleGenerate(`https://petstore3.swagger.io/api/v3/openapi.json`, [
        { ...sharedConfig, generator: 'typescript-react-query', output: `./typescript-react-query/src` },
        { ...sharedConfig, generator: 'typescript-axios', output: `./typescript-axios/src` },
        { ...sharedConfig, generator: 'typescript-axios', output: `./typescript-models/src`, modelsOnly: true },
        { ...sharedConfig, generator: 'c#', output: `./c#/src`, },
        { ...sharedConfig, generator: 'go', output: `./go/src` },
        { ...sharedConfig, generator: 'python', output: `./python/src` },
    ]);
})();

// use generate when you want only one output
(async () => {
    await generate({ pathOrUrl: `https://petstore3.swagger.io/api/v3/openapi.json`, generator: 'typescript-react-query', output: `./typescript-react-query/src` });
})();

Help output

openapi-toolkit <command>, default command 'generate'

Commands:
  generate    auto generate proxy client from swagger file             [default]
  generators  generators list
  completion  generate completion script

Options:
      --version                Show version number                     [boolean]
  -h, --help                   Show help                               [boolean]
  -i, --pathOrUrl              path or url for swagger file           [required]
  -o, --output                 output path                            [required]
  -g, --generator              generator name      [default: "typescript-axios"]
  -t, --type                   [choices: "client", "server"] [default: "client"]
  -n, --namespace                         [default: "OpenapiDefinitionGenerate"]
      --modelsFolderName                                     [default: "models"]
      --modelNamePrefix                                            [default: ""]
      --modelNameSuffix                                            [default: ""]
      --controllersFolderName                           [default: "controllers"]
      --controllerNamePrefix                                       [default: ""]
      --controllerNameSuffix                             [default: "Controller"]

Vscode Plugin For Auto Generate

Examples