Official venue APIsAPIfree
Manifold API: what it exposes, how it authenticates, where it stops
Last checked 2026-09-08
Manifold is a play-money prediction market whose API is the easiest on this site to start with: one header, a public base URL at https://api.manifold.markets, and the entire platform published under MIT on GitHub.
It is for researchers, bot builders and anyone learning market mechanics without real money, with the caveat that the API is still described as alpha.
What the API exposes
Market endpoints: GET /v0/markets (up to 1,000 per request), /v0/market/{id}, /v0/slug/{slug}, /v0/search-markets and POST /v0/market to create one. Trading: POST /v0/bet for bets and limit orders, /v0/multi-bet, /v0/bet/cancel/{id}, /v0/market/{id}/sell and GET /v0/bets for history. Users and portfolios: /v0/user/{username}, /v0/me, /v0/get-user-portfolio, /v0/market/{id}/positions.
Also documented: groups (topics), comments, transactions, managrams to send mana, and a beta perpetual futures set (place and close perp trades, positions, events, oracle price).
The WebSocket at wss://api.manifold.markets/ws (with a dev host at wss://api.dev.manifold.markets/ws) offers global/new-bet, global/new-contract, global/new-comment, contract/{marketId} and per-contract new-bet and new-comment topics. It needs a ping every 30 to 60 seconds to stay open.
Authentication and rate limits
Send Authorization: Key {key} using a key generated on your profile settings page, or Authorization: Bearer {jwt} with a Firebase token. The old host manifold.markets/api is deprecated in favour of api.manifold.markets.
The rate limit is 500 requests per minute per IP, and the docs prohibit dodging it with multiple IPs.
Pricing and access
Access is free and keys are self-serve. Actions cost mana rather than dollars: M$50 to create a binary market, M$250 for pseudo-numeric, M$25 per answer for multiple choice, M$1 per API comment. A CASH prize currency also exists.
Using API data to train commercial AI or ML models requires a data licence from data@manifold.markets; academic and personal use is allowed.
Where it falls short
It is play money, so nothing here transfers to a funded venue except the code structure. A market listed at 60% on Manifold is a crowd opinion, not a price anyone can arbitrage against Kalshi.
The docs call the API alpha and warn it may change or break at any time, and the per-IP limit means shared infrastructure can throttle you.
Who should use it
Students, researchers and bot authors who want a friendly sandbox with real order flow from a live community. The type definitions in common/src/api/schema.ts double as the most precise reference when the docs lag.
Anyone who needs dollar settlement should pair it with Kalshi or Polymarket rather than treating it as a venue.
Questions about Manifold API
Is the Manifold API free?
Yes. Keys come from your profile settings, and the only costs are in mana, the site's play money.
What is the Manifold API rate limit?
500 requests per minute per IP address.
Is Manifold open source?
Yes. github.com/manifoldmarkets/manifold is MIT licensed with the API type definitions in common/src/api/schema.ts.
Can I trade real money through the Manifold API?
No. Manifold uses mana, with a separate CASH prize currency. Commercial AI training on its data needs a licence.
Official APIs for building. One book for trading.
Rather trade the spread than build the plumbing? The free Kairos terminal gives you Kalshi, Polymarket and Predict.fun in one order book.