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Bellwether

Official registry Other

Live Kalshi + Polymarket prediction-market data and cross-venue arbitrage spreads, one schema.

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 bellwether 'https://api.bellwether.markets/mcp' --header 'X-API-Key: <Optional API key for higher rate limits (anonymous free tier: 120 req/hr)>'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "bellwether": {
            "type": "http",
            "url": "https://api.bellwether.markets/mcp",
            "headers": {
                "X-API-Key": "<Optional API key for higher rate limits (anonymous free tier: 120 req/hr)>"
            }
        }
    }
}

Frequently asked questions

What is Bellwether?

Live Kalshi + Polymarket prediction-market data and cross-venue arbitrage spreads, one schema.

How do I install Bellwether?

It runs as a remote server. In Claude Code: claude mcp add --transport http bellwether 'https://api.bellwether.markets/mcp' --header 'X-API-Key: <Optional API key for higher rate limits (anonymous free tier: 120 req/hr)>'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does Bellwether need an API key?

Yes. It expects X-API-Key, which you set in its configuration.

Who maintains Bellwether?

It is published by markets.bellwether. 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.