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The public API is served by the United Market backend. Use this API for market data, trading, order status, authentication, user profiles, comments, leaderboards, and real-time subscriptions. Only the public backend integration surface is documented here.
United Market is now live on BNB Smart Chain mainnet. We just launched — start trading on-chain prediction markets today.

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Calling Endpoints

Use HTTPS in the playground and browser clients. The HTTP endpoints redirect to HTTPS, which can make requests appear to fail from hosted docs. Some user-specific actions require SIWE authentication and a bearer token. Trading actions require EIP-712 order signatures. Open any endpoint page in this section to use the interactive playground.

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Endpoint Groups

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Common Conventions

  • Amounts are usually returned as raw token units. Collateral uses the collateral token decimals.
  • List endpoints such as GET /markets and GET /market-groups return { data, pagination } (page / pageSize, default 60, max 250), not a bare array.
  • Order identifiers are orderHash values derived from the signed EIP-712 order.
  • Public orders use the zero address as taker.
  • Market rooms and real-time events are keyed by conditionId.
  • Trading fees are quoted in basis points. Read a market’s effective rate from GET /markets/{id}/fee and sign it as the order’s feeRateBps. See Fees & Referrals.

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Errors

Most failures use Nest’s default JSON:
message can be a string or a validation array. A few handwritten responses omit error and only return { statusCode, message }. Treat statusCode + message as the stable fields.

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Rate limits

Responses include X-RateLimit-Limit-short / -medium, X-RateLimit-Remaining-*, and X-RateLimit-Reset-*. Exceeding a limit returns 429. short is per second, medium is per minute — they are independent, not perMin / 60. Limits depend on the route class and the key’s tier. The shared public web key is treated as anon. Fallback ceilings when a route has no class: DEFAULT is tighter than anon on many read classes on purpose. A named integration that 429s after switching off the web key needs PRO or MM, not a new DEFAULT key. Order-write / cancel budgets are separate and much tighter for anon. See API Keys.

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Order statuses

Public GET /orders?conditionId=… only returns filled and partially_filled. To see your own open quotes use GET /me/orders or GET /orders?account=<you> with credentials.