Polymarket market data
Polymarket market data: what the free API serves and what the archive adds
Polymarket's own API serves market metadata, a 1-minute price floor, the current book, and executed trades — all free. What has no free or official source is historical depth: PolyOrderbooks archives full L2 ladders every 250ms across [1.16 million markets and 2.5 billion snapshots](/polymarket-api-data).
Figures measured as of 2026-10-02 on the published PolyOrderbooks archive.
Short answer
Free data, and the one gap nobody fills
Polymarket market data splits cleanly in two. Live and per-market data is free from the official API: Gamma for metadata, outcomes, volumes, and liquidity; CLOB for prices (1-minute floor) and the current book; the Data API for executed trades; a websocket for live updates. None of it needs a key.
The gap is historical depth. The book endpoint returns the current ladder only and there is no archive behind it — depth is forward-only. If you need the book as it stood at any past moment, a stored 250ms archive is the only source.
Free
What the official API serves
The archive
What the archive adds
The PolyOrderbooks catalog spans more than 1.16 million markets — crypto up/down contracts at 5m, 15m, and 4h, price-threshold and event-linked, plus more than 700,000 sports markets across 226 series — with more than 2.5 billion stored L2 snapshots, all at 250ms.
One API key pages across both categories: discovery via /v1/markets, /v1/events, /v1/series, and /v1/tags; full L2 ladders per market at /books; aligned prices and metrics (spread, depth, volume over time) on the same timestamps; and per-token /tokens/{id}/books when a single outcome is the cleaner read.
Get it
Where to get it
- Official API — Gamma, CLOB, Data API, websocket; free and documented in what the API serves.
- PolyOrderbooks archive — full L2 books, prices, and metrics at 250ms over REST, free Starter with 3 days of history.
- Coverage pages — crypto and sports data coverage, measured.
- Open datasets — 897,192 snapshots across 805 resolved markets on Zenodo, CC BY 4.0.
FAQ
Is Polymarket market data free?
Mostly yes from the official API: Gamma serves market metadata, outcomes, volume, and liquidity; CLOB serves a 1-minute price floor and the current book; the Data API serves executed trades — all free and keyless. Historical order book depth is the exception, and it has to be captured.
What does the PolyOrderbooks archive cover?
More than 1.16 million crypto and sports markets and 2.5 billion L2 snapshots at 250ms, queried from one API key. Crypto includes up/down contracts at 5m, 15m, and 4h windows plus price-threshold and event markets; sports covers 700,000+ markets across 226 series.
Why is historical depth not in the official API?
The /book endpoint returns the current ladder only; there is no historical endpoint, no date parameter, and no archive behind it. Depth is forward-only — it exists for the past only if somebody recorded it while the market lived.
What fields does the archive return?
Each market resolves to full L2 bid/ask ladders with price levels and sizes, captured_at timestamp, and resolution metadata including the winning outcome and a crossed flag, at 250ms-to-1d query resolution. Prices and metrics align to the same timestamps.