Polymarket API & backtesting guides
Reference material we needed and could not find: exact rate limits, the errors that are missing from the official docs, and what prediction market data can and cannot tell you. Every number is sourced and every command is reproducible.
Polymarket API Rate Limits: The Complete Reference
Polymarket publishes its rate limits across several pages, in two completely different systems, using a 10-second window almost nobody expects. This is all of it in one table set — plus what actually happens when you cross a limit.
Polymarket API Errors: Every Code, Decoded
Polymarket's error messages are terse, and the ones that break your bot at 3am are usually the ones missing from the documentation entirely. Here is the full reference — documented errors, undocumented ones, and what to actually do about each.
Polymarket WebSockets: Real-Time Data That Does Not Drop
Polling the order book is the most common way to burn a rate limit budget for no benefit. Here are the four streams, the subscription options nobody documents, and the failure mode where your bot receives silence and calls it calm.
The Polymarket Python SDK in 2026 (and Migrating off py-clob-client)
If your code still imports ClobClient from py_clob_client, it is built on a superseded package — and so is most of the Polymarket code an AI assistant will write for you. Here is the current SDK and how to move.
The Polymarket API, Mapped: Gamma vs CLOB vs Data API
Newcomers lose a day to the same problem: Polymarket does not have an API, it has four of them, and the endpoint you want is rarely on the one you tried first. This is the complete map.
Does Polymarket Have a Testnet?
Short answer: no. Polymarket has never shipped a public testnet, and there is no sandbox environment or demo API. Your first real order is a real order, with real money, against real counterparties. Here is how experienced builders work around that.
Polymarket Up/Down Markets: Slugs, Resolution and the Data Cliff
Polymarket's crypto Up/Down markets are the highest-frequency instruments on the platform — and the most misunderstood. Here is how to decode a slug, what actually determines resolution, and a two-command demo of the data cliff that makes them so hard to study.
How to Choose a Polymarket Data API
Every provider markets a big number. Almost none of them market the number that matters. Here is what to actually test before you commit, including the cases where you do not need a paid provider at all.
Backtest against the data Polymarket deletes
90M+ point-in-time snapshots of Polymarket crypto Up/Down markets, with 8 levels of order book depth and sub-second timestamps — including markets that have already resolved.