Polymarket Market Data API Cheatsheet

Last verified: 2026-07-08 PDT

You do not need trading credentials to learn from Polymarket market data. Polymarket documents public APIs for discovery, prices, order books, spreads, history, positions, trades, holder data, and comments. This cheatsheet keeps the read-only research layer separate from authenticated trading.

This page is educational research content. It explains process, math, market structure, and recordkeeping. It does not tell you what to trade.

Key concepts in plain English

  • ▸Gamma API: Public discovery data for events, markets, descriptions, outcomes, prices, volume, liquidity, and metadata.
  • ▸CLOB API: Central limit order book data, including public order books, prices, spreads, midpoints, and price history; authenticated endpoints handle order operations.
  • ▸Data API: Public user, trade, position, activity, holder, leaderboard, and open-interest style data.
  • ▸Token ID: The outcome-token identifier used for CLOB price and order-book queries.
  • ▸Condition ID: A market identifier used for market lookup and price-history workflows.

The three API surfaces

Polymarket docs describe Gamma for discovery, CLOB for order-book and pricing data, and Data API for trades, activity, positions, holders, leaderboards, and builder analytics. Keep those lanes separate. Discovery tells you what exists. CLOB tells you what the book looks like. Data API helps with activity and holder context.

Read-only workflow

A safe monitoring setup starts with Gamma search or event lists, extracts markets, outcomes, outcome prices, token IDs, condition IDs, end dates, liquidity, volume, and rules, then uses CLOB public endpoints for book, price, spread, midpoint, and history checks. No order placement is needed for research dashboards or alerting.

Fields worth saving

Save market title, slug, question, description, resolution source, end date, outcomes, outcome prices, token IDs, condition ID, liquidity, volume, accepting-orders state, minimum size, tick size, and whether the market is negative-risk or combo-enabled. Those fields explain more than a raw price snapshot.

Alert ideas that are research-safe

Good alerts are not trade instructions. Useful examples: spread wider than a threshold, depth below a threshold, price moved more than X points since your last note, deadline within 24 hours, market rules changed in your local snapshot, or a related event crossed a scenario-tree gate.

Where builders get in trouble

The mistake is mixing read-only monitoring with automated execution before access, authentication, fee disclosure, geoblock state, order limits, and user-defined controls are clear. Treat the API as a research surface first. If a tool ever routes orders, it needs separate eligibility, authentication, cost, and kill-switch review.

Common mistakes

  • ▸Confusing Gamma outcomePrices with an executable fill price.
  • ▸Ignoring bid-ask spread and order-book depth.
  • ▸Forgetting token IDs are needed for CLOB price and book calls.
  • ▸Treating public data access as proof of trading eligibility.
  • ▸Building alerts that create urgency instead of review discipline.

Practical checklist

  • ▸Market slug and URL saved?
  • ▸Question and rule text saved?
  • ▸Outcome prices parsed from JSON strings?
  • ▸CLOB token IDs saved for Yes and No outcomes?
  • ▸Spread and depth checked?
  • ▸End date and resolution source logged?
  • ▸Alert has a research note, not an instruction?

Where Bucko fits

Bucko can help you keep market rules, probability notes, source links, price snapshots, liquidity checks, user-defined guardrails, and post-resolution reviews in one workspace. Treat Bucko as a research and journaling layer, not a promise about outcomes.

If you are eligible for the US app offer, use code BUCKO for a $50 deposit bonus on the Polymarket US app: https://www.poly.market/BUCKO. Confirm current app screens and offer terms before depositing.

Internal links

Sources and last-verified notes

Last verified: 2026-07-08 PDT.

Sources reviewed: Polymarket docs llms.txt and llms-full.txt; API overview describing Gamma API, CLOB API, Data API, public versus authenticated endpoints, order-book, pricing, spread, midpoint, and price-history references; Gamma active market samples checked on July 8, 2026 PDT.

Frequently Asked Questions

Is Polymarket market data public?
Polymarket docs describe Gamma and Data API as public, and CLOB read endpoints such as order books, prices, and spreads as public.
Do I need authentication for Polymarket research alerts?
For public discovery, order-book, price, spread, and many data workflows, authentication is not needed. Trading and order-management endpoints are separate.
What is the biggest API mistake beginners make?
They treat displayed probability as an executable fill and skip the spread, depth, rules, deadline, and source checks.

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