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21st.dev

Official registry Developer tools

Find UI components and themes, retrieve code, and generate with hosted 21st AI when enabled.

Website

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http 21st-dev 'https://21st.dev/api/mcp' --header 'x-api-key: <Your 21st.dev API key from https://21st.dev/settings/api-keys. Authentication is required for discovery and tool calls. Generation tools are listed only when the account has hosted AI access.>'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "21st-dev": {
            "type": "http",
            "url": "https://21st.dev/api/mcp",
            "headers": {
                "x-api-key": "<Your 21st.dev API key from https://21st.dev/settings/api-keys. Authentication is required for discovery and tool calls. Generation tools are listed only when the account has hosted AI access.>"
            }
        }
    }
}

Frequently asked questions

What is 21st.dev?

Find UI components and themes, retrieve code, and generate with hosted 21st AI when enabled.

How do I install 21st.dev?

It runs as a remote server. In Claude Code: claude mcp add --transport http 21st-dev 'https://21st.dev/api/mcp' --header 'x-api-key: <Your 21st.dev API key from https://21st.dev/settings/api-keys. Authentication is required for discovery and tool calls. Generation tools are listed only when the account has hosted AI access.>'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does 21st.dev need an API key?

Yes. It expects x-api-key, which you set in its configuration.

Who maintains 21st.dev?

It is published by dev.21st. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.