Getting started

FlashMCP turns any REST API with an OpenAPI spec into a fully-functional MCP server your LLM can use. One URL. Zero setup. No servers to deploy, no code to write, no dependencies to install — it just works.

FlashMCP is fully hosted on a global edge network. You point your MCP client at a URL and we handle everything else: discovering the spec, parsing every endpoint, resolving complex schemas, and building optimized tool definitions. It's magic.

Quick start

You can go from zero to a working MCP server in under a minute. Here's how:

Step 1: Pick an API

Choose any REST API that has an OpenAPI (formerly Swagger) specification. This covers thousands of popular APIs — Stripe, GitHub, Twilio, Notion, PagerDuty, and many more. If the API has a spec, FlashMCP can use it.

Step 2: Add FlashMCP to your MCP client

Open your MCP client configuration and add a new server entry. The URL is simply https://flashmcp.dev/ followed by the API's hostname.

{
  "mcpServers": {
    "petstore": {
      "url": "https://flashmcp.dev/petstore3.swagger.io"
    }
  }
}

That's it. No npm install. No Docker. No build step. FlashMCP runs entirely in the cloud — your MCP client connects to it over HTTP like any other hosted service.

Step 3: Use it

Restart your MCP client (or reconnect). Your LLM now has access to every endpoint in the API as a callable tool. Ask it to list resources, create records, update data, or delete items — all through natural language.

URL format

Every FlashMCP URL follows the same pattern:

https://flashmcp.dev/{targetHost}[/{basePath}][?spec={specPath}]

Examples

What gets mapped

FlashMCP reads the OpenAPI specification and turns every operation into an MCP tool your LLM can call. Each tool gets a name, a description, and a fully-typed input schema — all generated automatically.

Tool naming

If an operation has an operationId in the spec, that becomes the tool name directly. If not, FlashMCP generates a readable name from the HTTP method and path.

Supported HTTP methods

All five standard HTTP methods are fully supported:

• GET — Read resources
• POST — Create resources
• PUT — Replace resources
• PATCH — Partially update resources
• DELETE — Remove resources

LLM-optimized parameters

FlashMCP flattens request body schemas into simple, top-level parameters. Your LLM calls tools with clean, flat arguments — no nested objects or wrapper properties required. For example, instead of:

createPet({ body: { name: "Rex", status: "available" } })

Your LLM simply calls:

createPet({ name: "Rex", status: "available" })

Complex $ref pointers, nested schemas, allOf/oneOf/anyOf compositions, and even circular references are all resolved automatically. You never have to think about schema complexity — FlashMCP handles it.

Try it now

Copy and paste this configuration into your MCP client to connect to the Swagger Petstore demo API. It's a free, public API — no authentication required.

{
  "mcpServers": {
    "petstore": {
      "url": "https://flashmcp.dev/petstore3.swagger.io"
    }
  }
}

Once connected, your LLM will have access to every Petstore endpoint as a tool — including listPets, getPetById, addPet, updatePet, deletePet, and more. No server running on your machine, no configuration files to maintain, no updates to install.

Next up: learn how to customize your setup with configuration options, or see how to pass API keys with authentication.