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Last updated: August 2026

Polymarket Historical Data Guide

Polymarket does not hand you a historical price series. The live APIs return current state, so anything about the past has to come from on-chain records, an indexer built on them, a third-party provider, or data you recorded yourself. Which you choose determines what questions you can actually answer.

01.Why history is not simply an endpoint

The order book is current state, not an archive — the API tells you what is resting now, and once a level is consumed it is gone from that view. Trades that executed are recorded on-chain and so are recoverable, but reconstructing what the book looked like at a moment in the past means having captured it at the time. That distinction decides which strategies you can backtest.

  • Executed trades are on-chain and recoverable after the fact.
  • Historical order book depth is not, unless someone recorded it.
  • A strategy that depends on past depth cannot be backtested from public history alone.

02.The four sources

They differ in effort, completeness and whether you can trust them to still be there next year.

  • On-chain data: authoritative and complete for trades and settlements, but you do the reconstruction work.
  • Subgraphs and indexers: on-chain events pre-indexed into a queryable API. Much less work, and you inherit their schema decisions.
  • Third-party data providers: cleaned and ready, at a price, with a dependency you do not control.
  • Your own recording: the only way to get order book snapshots, and only from the day you start.

03.Start recording before you need it

This is the advice people wish they had taken. Book snapshots, spreads and depth only exist if something captured them at the time, and no amount of effort recovers them later. If there is any chance you will want that data, a small process writing periodic snapshots costs almost nothing and is irreplaceable once a few months have accumulated.

  • Snapshot the book on a schedule for markets you care about.
  • Record the full raw payload, not just the fields you currently use.
  • Timestamp everything consistently, ideally in UTC.

04.Survivorship bias will ruin your backtest

The specific trap in prediction market data is that it is easiest to gather history for markets that resolved cleanly and had volume. Markets that were cancelled, disputed, or died quietly are exactly the ones your dataset will be missing, and they are exactly the ones that would have hurt a live strategy. A backtest built only on well-behaved markets will look far better than reality.

  • Include cancelled, disputed and low-volume markets or know that you have not.
  • Record resolution outcomes as well as prices — disputes matter.
  • A backtest on clean markets only is a measure of the dataset, not the strategy.

Related Pages

DataPolymarket Indexers & OraclesWebsocket GuideDeveloper Tools

Frequently Asked Questions

Does Polymarket have a historical data API?▼
Not for price series. The live APIs return current state. Historical trades are recoverable from on-chain records or an indexer built on them, but past order book depth only exists if someone recorded it at the time.
How do I get historical Polymarket prices?▼
From on-chain trade data, a subgraph or indexer that has pre-processed it, a third-party data provider, or your own recorded snapshots. Several providers are listed in the Polymarket data category.
Can I backtest a Polymarket strategy?▼
For strategies driven by executed trades, yes, using on-chain history. For anything depending on order book depth or spread at the time, only if you recorded that data yourself — it is not publicly archived.
What is the biggest mistake in backtesting prediction markets?▼
Survivorship bias. Clean history is easiest to obtain for markets that resolved cleanly and had volume, so cancelled, disputed and abandoned markets go missing — and those are exactly the ones that would have hurt the strategy live.
Should I record my own data?▼
If there is any chance you will want order book history, yes, and start before you need it. Snapshots cannot be recovered retroactively, and a few months of accumulated recording is irreplaceable.