Can FastMCP turn an OpenAPI spec into an MCP server?

Yes. FastMCP.from_openapi() takes the spec and an HTTP client and makes a tool for each endpoint by default; route maps can turn endpoints into resources or leave them out. FastMCP's docs say models do significantly better with curated servers than with auto-converted ones, and recommend generation for bootstrapping and prototyping.

Yes. The framework is open source under Apache 2.0. Prefect Horizon, the managed platform from the same team, has a free Personal plan for one developer and a Developer plan at $35 per developer a month plus usage.

Do I need to write code to use Kaiva Bridge?

No. You connect a source in the console or with the CLI and choose which tools to switch on. For logic that no API or database already provides, write a server with an MCP framework such as FastMCP, then add it to Bridge as a remote MCP server if you like.

COMPARISON

Kaiva Bridge or FastMCP

Checked 15 Oct 2026, from each product's own docs and pricing pages.

FastMCP is an open-source Python framework (Apache 2.0) for writing MCP servers in code, made by Prefect, which also runs Prefect Horizon to deploy FastMCP servers from GitHub. Kaiva Bridge is a managed MCP cloud platform: you point it at an API spec, a database, a spreadsheet or documents and get a live MCP server without writing or deploying code. Choose FastMCP when you want to write the tools yourself, control every line and run the server where you like. Choose Kaiva Bridge when what your AI needs already exists as an API, a database or files, and you would rather connect it than build and maintain a server.

Side by side

FastMCP and Kaiva Bridge, side by side, checked 15 Oct 2026
What	FastMCP	Kaiva Bridge
What it is	FastMCPAn open-source Python framework for writing MCP servers, clients and apps, made by Prefect. A TypeScript version is maintained by the same team.	Kaiva BridgeA managed MCP cloud platform. You connect a source, Bridge builds the tools from it and serves the MCP server.
What it connects	FastMCPAnything your code can reach: you write each tool as a Python function. FastMCP.from_openapi() generates tools from an OpenAPI spec.	Kaiva BridgeREST APIs from an OpenAPI 3.x or Swagger 2.0 spec, a cURL command or a Postman collection (v2.0 or v2.1); GraphQL APIs (their queries); Postgres, MySQL, MariaDB and SQL Server databases (read-only); CSV spreadsheets; documents (PDF, Word, PNG, JPEG, text and Markdown); and existing remote MCP servers.
How you build a server	FastMCPWrite Python with the @mcp.tool decorator, or pass an OpenAPI spec and an HTTP client to FastMCP.from_openapi(), which makes every endpoint a tool by default and lets you map routes to tools, resources or nothing.	Kaiva BridgeConnect the source in the console, with the CLI (npx @kaiva/bridge push) or from your AI client through the Kaiva Bridge connector, then choose which tools to switch on. No server code to write.
How you run it	FastMCPWherever you choose: on your machine, on your own servers, or on Prefect Horizon, which deploys it from a GitHub repository and redeploys on every push to main.	Kaiva BridgeKaiva runs it. When you publish, the server is live at an address on api.kaiv.ai, over Streamable HTTP.
Sign-in for AI clients	FastMCPOff by default. You add an auth provider: JWT verification, OAuth through a provider that supports dynamic client registration, an OAuth proxy for providers that do not (GitHub and Google among them), or your own OAuth server. On Horizon, switch on Authentication and Horizon handles OAuth.	Kaiva BridgeOAuth 2.1 sign-in with a Kaiva account on every plan, so Claude and ChatGPT need no key, or a gateway key limited to the servers you pick.
API credentials	FastMCPSet on the HTTP client your code creates, for example as an Authorization header.	Kaiva BridgeStored encrypted by Bridge, added to each call on the server side and never sent to the AI client.
Pricing	FastMCPThe framework is free. Prefect Horizon: Personal is free for one developer; Developer is $35 per developer a month plus usage; Enterprise has custom pricing.	Kaiva BridgeFree: 10 servers and 200,000 tool calls a month, no card. Pro: $19 a month for unlimited servers and 1,000,000 tool calls, then $0.04 per 1,000 calls. Enterprise by contract.
Open source	FastMCPYes, Apache 2.0. Prefect Horizon is a commercial service.	Kaiva BridgeThe CLI is open source (MIT). The platform is not.
Where it runs	FastMCPAnywhere Python runs. On Horizon, at an address such as your-server-name.fastmcp.app/mcp.	Kaiva BridgeKaiva's managed cloud. A source must be reachable on the public internet: Bridge refuses private and internal addresses.
Team features	FastMCPPrefect Horizon adds a server registry and audit logs. Role-based access down to the tool, SSO and directory sync are on its Enterprise plan.	Kaiva BridgeOn every plan, per-tool switches and a log of every call. On Pro, SSO, approval before chosen calls and alerts.

Which to choose

Choose FastMCP if

You want to write every tool yourself, in Python or TypeScript, and control exactly what each one does, including tools that combine several calls or run your own logic.
Your API is large or complex and you want a small, hand-designed set of tools. FastMCP's docs say models do significantly better with curated servers than with servers converted automatically from OpenAPI.
You want the server in your own repository, with your own tests, CI and code review.
You need to run it yourself: on your laptop, inside your network or in your own cloud account.
You are also building MCP clients or interactive MCP apps, which FastMCP covers too.

Choose Kaiva Bridge if

What your AI needs already exists as a REST or GraphQL API, a Postgres, MySQL, MariaDB or SQL Server database, a spreadsheet or a set of documents, and you would rather connect it than write a server.
You want a working address with no deploy step, no runtime and no server to keep up to date.
You want Claude, ChatGPT, Cursor and VS Code to sign in with OAuth without choosing or configuring an auth provider.
You want database tools that cannot change data: every query runs in a read-only transaction.
Your API has no OpenAPI spec, but you have a cURL command or a Postman collection.
You want a coding agent to create a server from a public API spec with no account (the spec's GET operations, for 72 hours), and claim it into your workspace later.

Using both

The two work together. Serve your FastMCP server over Streamable HTTP and add its address to Kaiva Bridge as a remote MCP server: Bridge records its tools, serves them from a Bridge address with the same sign-in as your other Bridge servers, and keeps the FastMCP server's own key on the server side.

Questions

Can FastMCP turn an OpenAPI spec into an MCP server?: Yes. FastMCP.from_openapi() takes the spec and an HTTP client and makes a tool for each endpoint by default; route maps can turn endpoints into resources or leave them out. FastMCP's docs say models do significantly better with curated servers than with auto-converted ones, and recommend generation for bootstrapping and prototyping.
Is FastMCP free?: Yes. The framework is open source under Apache 2.0. Prefect Horizon, the managed platform from the same team, has a free Personal plan for one developer and a Developer plan at $35 per developer a month plus usage.
Do I need to write code to use Kaiva Bridge?: No. You connect a source in the console or with the CLI and choose which tools to switch on. For logic that no API or database already provides, write a server with an MCP framework such as FastMCP, then add it to Bridge as a remote MCP server if you like.

Sources

Read on 15 Oct 2026. Prices and features change, so check these pages before you decide. If something here is out of date, email [email protected] and we will correct it.

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