# Manifold API

Every read is keyless, the server is MIT-licensed, and the currency is play money.

*https://predictionmarkets.tools/tools/manifold-api · Prediction Market Data APIs*

## Facts

### At a glance

| Field | Value |
| --- | --- |
| Vendor | Manifold |
| Category | Prediction Market Data APIs |
| Job | realtime |
| Website | https://api.manifold.markets |
| Pricing model | free |
| Free tier | true |
| Open source | true |
| Licence | MIT |
| Self-hosted | false |
| Tested hands-on | false |
| Last updated | 2026-09-19 |

### Availability

| Field | Value |
| --- | --- |
| Jurisdictions | global |
| Open to US persons | true |
| KYC required | false |

### Markets

| Field | Value |
| --- | --- |
| Subjects | politics, sports, macro, crypto, science, culture, business |
| Settlement | play_money |
| Resolved by | Whoever created the question resolves it through the same API that reads it; moderators and staff are the only accounts that can annul one. |

### Economics

| Field | Value |
| --- | --- |
| Taker fee | none |
| Maker fee | none |
| Liquidity model | amm |
| Platforms | library |
| AI features | none |

### Interfaces

| Field | Value |
| --- | --- |
| API | true |
| WebSocket | true |
| Scripting | none |
| Python | false |
| MCP server | false |
| Export | json |

### Capabilities

Yes: order_book, automation, live_trading, portfolio_tracking

No: charting, screening, backtesting, paper_trading, calibration_scoring, cross_venue, alerts, news, tax_reporting

*Verified: pricing 2026-09-19; availability 2026-09-19.*

## What it is

The whole of Manifold, exposed. Fifty-odd documented endpoints cover users, portfolios and
portfolio history, topics, questions, search, probabilities, positions, trades, comments,
leagues and the transaction ledger, plus a perpetuals surface with its own oracle price and price
series endpoints. Every read is keyless; every write takes a single `Authorization: Key` header
from a key you generate on your own profile page.

What makes it unusual in this category is that the server is the same MIT-licensed repository the
site runs on. When the documentation is ambiguous, `common/src/api/schema.ts` in
`manifoldmarkets/manifold` is the actual contract — parameters and return types, not prose — and
the docs page itself is a Markdown file in that repo that you can send a pull request to. The
default branch was last pushed to on 18 September 2026.

Real time is a WebSocket at `wss://api.manifold.markets/ws` with a topic-subscription protocol,
including a per-market topic for updates to resting limit orders. It needs a ping every 30 to 60
seconds; go quiet for 60 and the connection is closed.

## Availability

No account is needed to read and no identity check to write: a key belongs to a Manifold account,
and a Manifold account is an email address. There is no geographic gate on the API host, which
answered this machine without credentials on 19 September 2026.

The constraint here is not jurisdictional, it is contractual. Use of the API is subject to the
site's terms, which permit bots, automated trading systems and integrations, prohibit scraping the
site by any means other than the API, prohibit circumventing rate limits, and reserve the right to
suspend access for abuse or excessive usage. The AI-training clause is the one most likely to
matter to a reader here — see Limitations.

## Pricing

Free, with no plans, no metering and no paid tier. The only charge documented anywhere in the API
reference is internal to the play-money economy: a comment placed through the API costs M1.

Because the currency is mana and mana cannot be withdrawn, there is no taker fee, no maker rebate
and no settlement fee to record on this card — the `economics` block is null rather than zero on
purpose. What a position costs you is the AMM's price impact, and that is a property of the
question rather than a fee schedule.

The rate limit is the real ceiling: 500 requests a minute per IP, shared across every endpoint.

## Markets & resolution

Anything anyone opens, which in practice is every category this catalogue tracks and a long tail
that none of the money venues would list. The API is also how questions get *created* and
*resolved* — `POST /v0/market` and `POST /v0/market/[marketId]/resolve` are ordinary endpoints,
and the account that created a question is the account that settles it. Only moderators and staff
can annul one to N/A.

That is the whole difference between this feed and every other one in the category. A price here
is a crowd's estimate priced in a currency that buys nothing, and the resolution behind it is one
person's judgement rather than an exchange's rulebook or an oracle vote. Treat a Manifold
probability as a forecast, not as a quote.

Two naming traps that will bite the first integration. A topic is called a **group** in the code
and in the API, not a tag. A question is a **contract** in the code and sometimes a **market** in
the API, and both spellings appear in the same document. All times are UNIX milliseconds.

## Integrations

REST plus the WebSocket, and nothing else first-party: there is no official Python or TypeScript
client, no MCP server and no SDK published by the vendor. The community packages that exist are
not named in the documentation, which is the honest way to read that absence.

Pricing mechanics leak into the API in a way worth knowing before writing an execution path.
Manifold is a CPMM automated market maker with resting limit orders on top: an order carrying
`limitProb` fills against the curve and against other people's unfilled orders up to that price,
and whatever is left rests until it is cancelled or expires. `expiresAt` and `expiresMillisAfter`
are parameters on the order itself. Open orders come back from the trades endpoint with
`kinds=open-limit`, including on closed and resolved questions.

## Limitations

- **It is alpha, and says so.** The documentation's own caution block warns that things may change
  or break at any time, and that the legacy `manifold.markets/api` host will disappear eventually.
- **The bulk dumps are two years stale.** The free markets, trades and comments archives on the
  data page are dated 6 July 2024, and there is no newer public dump. Current history means paging
  the API.
- **Commercial AI training needs a licence.** Academic, personal and non-commercial use of API
  data is permitted; training models for commercial purposes is not, without a separate data
  licence from the vendor.
- **Nothing here is money.** No withdrawal, no settlement in dollars, and no regulator — which is
  the point, and which rules this feed out for anyone pricing a real position.
- **One key per account**, refreshed rather than rotated: generating a new one invalidates the old.
- **No official client library in any language**, so the signing, retry and pagination code is
  yours.

## Alternatives

For the same shape of data with money behind it and no key to read, the
[Polymarket Gamma API](https://predictionmarkets.tools/tools/polymarket-gamma-api) and the
[Kalshi API](https://predictionmarkets.tools/tools/kalshi-api) are the direct comparisons. If Manifold is wanted alongside other
venues in one schema, [FinFeedAPI](https://predictionmarkets.tools/tools/finfeedapi) normalizes it with eight others, at the price
of a bill per request. And if what is actually wanted is a scored forecasting record rather than a
tradable price, the platform itself — [Manifold](https://predictionmarkets.tools/tools/manifold) — publishes its own calibration,
and [Metaculus](https://predictionmarkets.tools/tools/metaculus) is the reference point for that job.

## FAQ

### Does the Manifold API need a key?

Only for writes. Every GET endpoint answers unauthenticated — a call to the markets endpoint returned live records with no headers on 19 September 2026 — while POST routes need an Authorization header carrying a key generated on your profile page. Each account may hold zero or one key.

### What is the Manifold API rate limit?

500 requests per minute per IP, stated in the documentation, with an explicit request not to spread traffic across addresses to get around it.

### Can I train a model on Manifold data?

Not commercially without a licence. The terms permit academic research, personal projects and non-commercial use, and require a data licence from the vendor for AI or ML training for commercial purposes. Scraping the site by any route other than the API is prohibited outright.

### Are there bulk data dumps?

Yes, for markets, trades and comments going back to December 2021, free and non-commercial — but the files published on the data page were last refreshed on 6 July 2024. Anything newer than that has to come through the API.

### Is the Manifold API stable?

The documentation calls it alpha and says things may change or break at any time. It also notes that the API moved off manifold.markets/api onto its own domain and that the old host will disappear at some point.

## Also from Manifold

- [Manifold](https://predictionmarkets.tools/tools/manifold.md)

## Background

- [Where weather data comes from and what you may do with it](https://predictionmarkets.tools/guides/where-weather-data-comes-from.md) — Observations, model output and archives are three products with three licences. The forecast is the cheap half; a clean observation history is not.

- [Why the same contract costs two different prices on two venues](https://predictionmarkets.tools/guides/why-the-same-contract-costs-two-prices.md) — Two venues quoting one outcome are quoting two contracts. What the gap between the prices is made of - rules, fallbacks, fees, collateral, exits, eligibility.
- [What a trade actually costs on a prediction market](https://predictionmarkets.tools/guides/what-a-trade-actually-costs.md) — Venues publish trading fees in four incompatible units, so 3.00% on one can be cheaper than 1.75% on another. How to convert them, and what else takes a cut.

## Also worth comparing

- [Futuur API](https://predictionmarkets.tools/tools/futuur-api.md) — One question, two order books — play money and real money, selected per request.
- [Kalshi API](https://predictionmarkets.tools/tools/kalshi-api.md) — REST, WebSocket and FIX access to a CFTC-regulated event exchange.
- [Limitless API](https://predictionmarkets.tools/tools/limitless-api.md) — REST and WebSocket for markets, books, candles and trading on Base.
- [Polymarket CLOB API](https://predictionmarkets.tools/tools/polymarket-clob-api.md) — Order books, prices and order placement on Polymarket's matching engine.
- [Polymarket Gamma API](https://predictionmarkets.tools/tools/polymarket-gamma-api.md) — Polymarket's read-only catalogue of events, markets, series and tags.
- [Polymarket US API](https://predictionmarkets.tools/tools/polymarket-us-api.md) — A keyless public gateway for reading, and a signed key behind KYC for trading.

## Named as a replacement for

- [Metaforecast](https://predictionmarkets.tools/alternatives/metaforecast.md)