One market can have three identifiers

A market can have one question and three identifiers. That is not duplication; it is a map of which system owns the next step.

Polymarket's market-details documentation assigns the market ID, slug, and condition ID to different jobs. Treating them as interchangeable is how a clean pipeline starts returning the wrong record.

Give each identifier a job

The market ID is used to fetch a known market by its Gamma ID. The slug is the readable link and lookup handle. The condition ID is used for public analytics, positions, and some trading or lifecycle workflows.

Store all three when you first discover the market. A later request should select the identifier from the operation it is about to perform, not from whichever field happened to be easiest to copy.

Keep discovery separate from execution

A slug can make a page easy for a person to read, but an order workflow may need an outcome asset ID and a condition ID. A market ID can find metadata without proving that an order book is ready.

The mapping belongs in the data model. Do not pass a human-readable link through the same field used for an authenticated trading request.

Version the outcome step

The market also describes whether an outcome uses a CTF token ID, a Protocol V2 position ID, or both. The documented market version determines which identifier to select for trading.

Read the version and outcome fields together. The presence of both fields does not, by itself, choose the protocol or the correct asset ID.

Make joins explicit

When joining market metadata to analytics or order records, keep the identifier name in the join key. A condition ID match and a market-slug match are not the same evidence, even when they point to the same question today.

The useful question is not whether the IDs look related. It is whether the identifier you carried forward is the one the next API expects.

Further reading: Market details · Discover markets · Place orders.

Explore the markets: Open Polymarket (referral link).