# Polymarket Gamma API

Polymarket's read-only catalogue of events, markets, series and tags.

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

## Facts

### At a glance

| Field | Value |
| --- | --- |
| Vendor | Polymarket |
| Category | Prediction Market Data APIs |
| Job | realtime |
| Website | https://docs.polymarket.com/market-data/overview |
| Pricing model | free |
| Free tier | true |
| Open source | false |
| Licence | none |
| 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, crypto, macro, culture, business |
| Settlement | crypto |
| Resolved by | Each market carries its own rules and named source; the outcome is proposed to the UMA optimistic oracle and, if contested, decided by a UMA token-holder vote. |

### Economics

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

### Interfaces

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

### Capabilities

Yes: none

No: charting, screening, order_book, backtesting, automation, live_trading, paper_trading, portfolio_tracking, calibration_scoring, cross_venue, alerts, news, tax_reporting

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

## What it is

The read half of Polymarket. Gamma is a plain REST service at `gamma-api.polymarket.com` that answers what is listed and what it means: events and their child markets, the series a recurring market belongs to, sports fixtures and teams, tag taxonomies, and a search endpoint. Every record carries the fields a catalogue needs — slug, condition ID, outcome token IDs, start and end dates, the resolution rules text, and the liquidity and volume figures Polymarket publishes about itself.

It is a separate product from the CLOB API and is bought by different people. Gamma is what you call to build a page, a screener, a research dataset or a market index. Nothing in it prices an order or places one, and no part of it requires a wallet.

The two identifiers that matter come out of here: the `conditionId` for the market and the token ID for each outcome. Both are what every other Polymarket surface is keyed by.

## Availability

Unrestricted as far as Polymarket documents it. The endpoints take no credentials, so there is no account to be refused and no jurisdiction attached to a request.

That is worth separating from the platform underneath. Polymarket's international site tells a US visitor that trading is blocked and offers to continue in view-only mode, pointing at [Polymarket US](https://predictionmarkets.tools/tools/polymarket-us) — a different entity, operating as a CFTC-designated contract market, with its own documentation and its own API. Gamma is the international platform's data service. A US reader may read it; what they may not do is trade the markets it describes on that platform.

The practical consequence for anyone building: Gamma will happily serve you a market your users cannot take a position in. Availability has to be enforced by your application, because the data layer does not carry it.

## Pricing

Free, with nothing to buy. Polymarket sells no data plan, no tier and no key for the read endpoints, and the builder programme is about routing orders rather than about reading markets.

The limit that bites instead is undocumented. Polymarket's builder tiers list API rate limits as Standard for unverified and verified builders and Highest for partners, without stating what any of those are in requests per second. Treat the absence as a reason to implement backoff, not as an absence of limits.

## Markets & resolution

Gamma describes markets it does not resolve. Resolution on Polymarket runs through the UMA optimistic oracle: an outcome is proposed against a bond (the docs give roughly 750 pUSD), there is a two-hour challenge window, a first dispute triggers a second proposal round, and a second dispute escalates to a vote of UMA token holders after a 24 to 48 hour debate period. Undisputed, that is about two hours; disputed, Polymarket's own timeline says four to six days.

Two fields on a Gamma record are worth more attention than they usually get. The rules text is where the actual source and the edge cases live — the question title is only the question. And a UMA vote can return "Unknown", in which case the market resolves 50/50 and every token, on both sides, redeems at 50 cents. Code that assumes a binary payout will mis-book that day.

Markets are grouped as events with child markets, which is the shape that surprises people coming from an exchange API: one event, many tradeable questions, each with its own pair of outcome tokens.

## Integrations

REST and JSON, cursor-paginated through the keyset variants of the list endpoints. Polymarket publishes unified SDKs that cover this surface — the Python one is `polymarket-client`, whose `AsyncPublicClient` lists markets with no credentials — and an OpenAPI description of Gamma is linked from the documentation index.

There is no WebSocket here. Real-time on Polymarket comes from the CLOB market channel and from a separate live-data stream, both documented on the trading side.

## Limitations

- **No order book, no prices beyond what the record carries.** Any question about the current spread goes to a different host.
- **No price history.** The series endpoint lives on the Data API, not on Gamma, and is keyed by token ID rather than by market slug.
- **No published rate limit.** You will discover yours in production.
- **No stream.** Keeping a large catalogue fresh means polling, and the polling budget is the undocumented number above.
- **Volume and liquidity figures are Polymarket's own.** They are the platform's numbers about the platform's markets, computed however Polymarket computes them, and nothing in the API explains the method.

## Alternatives

For prices, books and order placement on the same venue, the sibling product is the [Polymarket CLOB API](https://predictionmarkets.tools/tools/polymarket-clob-api) — same markets, different preconditions. If what you want is a regulated US exchange with a documented rate-limit table and settled-market archives, the [Kalshi API](https://predictionmarkets.tools/tools/kalshi-api) is the closest equivalent in shape. On Base, with its own REST and WebSocket surface, [Limitless API](https://predictionmarkets.tools/tools/limitless-api) covers a smaller and much shorter-dated market list.

## FAQ

### Do I need an API key for the Polymarket Gamma API?

No. Every Gamma endpoint documented as market data answers an unauthenticated GET. A plain request to the markets endpoint returned live market records on 19 September 2026 with no credentials of any kind attached.

### What is the difference between the Gamma API and the CLOB API?

Gamma answers what exists — events, markets, series, tags, teams and the rules text attached to them. The CLOB API answers what it costs, with order books, prices and order placement. Most integrations call both, and they are separate products with separate preconditions.

### Does the Gamma API give me price history?

No. Gamma carries market metadata and current state. Price series live on Polymarket's Data API, at the prices-history endpoint, keyed by the outcome token ID you get from Gamma.

### What rate limit does Gamma enforce?

Polymarket does not publish one. Its builder tier table names API rate limits as Standard or Highest without numbers, so the only safe design is to back off on errors rather than to plan against a documented ceiling.

## Also from Polymarket

- [Polymarket CLI](https://predictionmarkets.tools/tools/polymarket-cli.md)
- [polymarket-client](https://predictionmarkets.tools/tools/polymarket-client.md)
- [Polymarket CLOB API](https://predictionmarkets.tools/tools/polymarket-clob-api.md)
- [Polymarket US API](https://predictionmarkets.tools/tools/polymarket-us-api.md)
- [Polymarket US Python SDK](https://predictionmarkets.tools/tools/polymarket-us-python.md)
- [Polymarket US TypeScript SDK](https://predictionmarkets.tools/tools/polymarket-us-typescript.md)
- [Polymarket US](https://predictionmarkets.tools/tools/polymarket-us.md)
- [Polymarket](https://predictionmarkets.tools/tools/polymarket.md)
- [py-clob-client](https://predictionmarkets.tools/tools/py-clob-client.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.
- [Limitless API](https://predictionmarkets.tools/tools/limitless-api.md) — REST and WebSocket for markets, books, candles and trading on Base.
- [Kalshi API](https://predictionmarkets.tools/tools/kalshi-api.md) — REST, WebSocket and FIX access to a CFTC-regulated event exchange.
- [Manifold API](https://predictionmarkets.tools/tools/manifold-api.md) — Every read is keyless, the server is MIT-licensed, and the currency is play money.
- [Adjacent](https://predictionmarkets.tools/tools/adjacent.md) — Prediction-market indices and reference rates, with Kalshi on the tier you can test.
- [Apify prediction-market scrapers](https://predictionmarkets.tools/tools/apify-prediction-market-scrapers.md) — A store of third-party actors that normalize Kalshi and Polymarket into one row shape.

## Named as a replacement for

- [Dome API](https://predictionmarkets.tools/alternatives/dome.md)