GET/oi

Get open interest

**Data API v2:** this route has a v2 counterpart, `GET /v2/oi`. See [Migrating to Data API v2](/migrate/data-api-v1-to-v2).

Base URL: https://data-api.polymarket.com
Auth: Public, no key
Rate limit: 1,000 req / 10s (100 per second)
Limit applies to: Data API general

Things to know

Data API v1 has been frozen since 4 September 2026. It still answers, but new fields and endpoints only go to v2. The v2 version of this call is GET /v2/oi.

Parameters

Name	In	Type	Required	Description
market	query	object[]	no

Example

curl -X GET "https://data-api.polymarket.com/oi"

Returns a list of objects with these fields

Field	Type	Description
market	string	0x-prefixed 64-hex string
value	number

Responses

Status	Meaning
200	Success
400	Bad Request
500	Server Error

Related endpoints

GET /v2/oi Data API v2

Polymarket's API serves current state only, so it cannot show what a market's book looked like after it resolved. PolyTest records Up/Down markets while they run and keeps the snapshots. Try it free, or read the full rate limit reference.

From Polymarket's published OpenAPI spec and rate-limit tables, synced 2026-10-04.