Bellwether
Free plan · From $49/mo
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Use
- For
- Independent developers and AI agents building on Kalshi and Polymarket prediction market data
- Price
- Free plan · From $49/mopricing page, read Oct 26, 2026
- Runs as
- API
- Used for
- find price spreads for the same event across Kalshi and Polymarket
- list and search open markets across both venues
- let AI agents query markets and spreads via MCP tools
- Has an MCP server (1 in the registry)public registry →
Free plan · From $49/mo
- Domain since2026domain registered
- Raised$40M · Series Bper the press · 2020-07 ↗
- MCP servermarkets.bellwether/prediction-marketsverified in the MCP registry
- Stateanswers, 3 toolschecked 2026-10-26
- Address to connectapi.bellwether.markets/mcp
- OpenAPI spec4 pathsthe spec ↗
- API docsbellwether.markets/docsthe vendor's page ↗
This card as JSON, for your agent →
Each line is something a program found when it went looking: the registry entry, the server's own answer, a spec that parses. A missing line means we did not find it, not that it does not exist.
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No notes yet. What do you use Bellwether for?
Sign in to leave a noteWhat is Bellwether?
Normalizes Kalshi and Polymarket markets, prices and volumes into one schema, and matches same-event contracts across both venues with price spreads.
Who is Bellwether for?
Independent developers and AI agents building on Kalshi and Polymarket prediction market data
How much does Bellwether cost?
Bellwether has a free plan; paid plans start at $49/mo, per its pricing page on 2026-10-26.
Is Bellwether free?
Yes, Bellwether has a free plan, per its pricing page on 2026-10-26.
Do people use Bellwether?
Little sign of use.
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