Bellwether

markets.bellwetherPublished by bellwether.marketsOfficial publisherv0.1.0Updated Oct 24, 2026

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

VerifiedStreamable HTTPWeb executableFinance

Overview

AI-generated overview

Gives an assistant live Kalshi and Polymarket prediction-market data and cross-venue arbitrage spreads in one schema.

What you can do
Bellwether exposes live prediction-market data from Kalshi and Polymarket through a single normalized schema, so an assistant can query markets and prices across both venues without reconciling their differing formats. It also surfaces cross-venue arbitrage spreads between the two. The manifest lists no individual tools, so the exact operations are not documented here.
When to use it
Worth adding when an assistant needs current prediction-market prices, odds, or cross-venue arbitrage spreads from Kalshi and Polymarket, for example for market research or comparison work.
Requirements
A remote streamable HTTP endpoint at api.bellwether.markets; no local runtime or package is needed. An optional X-API-Key header raises rate limits; the anonymous free tier allows 120 requests per hour. Network access is required.
Before you install
The optional X-API-Key header is a secret and should be supplied as a credential, not shared. The server is read-only market data as described, but the manifest lists no tools, so verify what it can do before relying on it. Data comes from third-party venues.

Installation

In SourceWeft

  1. Open Bellwether in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/markets.bellwether%2Fprediction-markets/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "bellwether": {
      "type": "http",
      "url": "https://api.bellwether.markets/mcp"
    }
  }
}

Tools

3

list_markets

List open prediction markets across Kalshi and Polymarket (normalized).

Parameterslimitvenue

get_market

Get one normalized market. venue is 'kalshi' or 'polymarket'.

Parametersvenuerequiredmarket_idrequired

matching_markets

Find the same real-world event on both venues, with the YES price spread.

Parameterslimitthreshold

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

72% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts

    Publish an icon in the registry entry.

  • Documentation15 pts

    Declare a GitHub repository with a README, or serve resource_documentation in the OAuth protected-resource metadata.

  • LicenseNot applicable

    A hosted service is used under its provider's terms, so no license is expected here. This check is left out of the percentage.

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