Polymarket Gamma API

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 — 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 the request rate. Polymarket's rate-limit page, read on 1 October 2026, gives Gamma 4,000 requests per 10 seconds overall and less per endpoint: 500 for /events, 300 for /markets, 900 for the two listings combined, 350 for /public-search, 200 each for /comments and /tags. The limits are per IP and enforced by Cloudflare, which throttles a request over the limit — delays or queues it — rather than rejecting it. A poller that overruns does not get errors to back off on; it gets slower answers.

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 the separate live-data streams documented on the trading side. Those are mid-move: since 15 September 2026 PolyBolt carries the crypto and equity reference prices and needs CLOB API credentials; RTDS keeps the public activity topic, and its price topics are deprecated, planned for removal one month after the TypeScript SDK's 0.11.0 release; the live comments stream is being retired with no streaming replacement. What each Polymarket API holds maps all of them.

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 lives on the Data API at /v2/prices-history and, in its older form, on the CLOB host — not on Gamma — and is keyed by token ID rather than by market slug.
• Throttled, not rejected. Over the per-endpoint limit, Cloudflare delays requests instead of returning an error, so a poller that overruns sees latency rather than a status code it can react to.
• No stream. Keeping a large catalogue fresh means polling, and at 300 requests per 10 seconds on /markets the polling budget is the 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 — same markets, different preconditions. If what you want is a regulated US exchange with settled-market archives, the Kalshi API is the closest equivalent in shape. On Base, with its own REST and WebSocket surface, Limitless API covers a smaller and much shorter-dated market list.

For who traded, who holds what and the price series, the third sibling is the Polymarket Data API, keyless like this one. If the goal is live prices on a web page rather than an integration, Polymarket Embeds is the venue's own no-code iframe builder, and PredictWidget is a third-party two-line script that shows the highest-volume markets but cannot show one you pick.

If all you want is the slice of this list tied to a stock or ETF - up-or-down, price-target and earnings questions - Adanos reads it hourly and files each market under its ticker, with trades, liquidity and which way the odds lean rolled up, so you do not walk /markets and do the mapping yourself. The free plan is 250 calls a month; the full per-market rows start at 299 USD.