Exchange: Cancel

Alpha Version

The Ostium Builder Service is in Alpha. API endpoints, specifications, and builder URLs may change without notice. Use with caution in production environments.

POST /v1/exchange/cancel

Builds unsigned transactions to cancel pending limit orders or cancel stuck market orders (timeouts).

Headers

Header	Required	Description
`X-Trader-Address`	Yes	Trader wallet address.
`X-API-Key`	No	Delegated mode (delegate wallet must be verified).
`Content-Type`	Yes	`application/json` or `text/plain` (JSON string).

Request Body

Field	Type	Required	Description
`cancels`	`CancelItem[]`	Yes	One or more cancel actions.

CancelItem

Field	Type	Required	Description
`t`	`string`	Yes	Cancel type: `limit`, `open`, `close`.
`a`	`number`	Cond.	Pair index (required for `limit`).
`i`	`number`	Cond.	Order index (required for `limit`).
`o`	`number`	Cond.	Order ID (required for `open` or `close` timeouts).

Constraints

cancels must contain at least one item.
limit cancels require a and i.
open or close cancels require o (order ID).
Delegated mode supports one cancel per request.

Response Body (unsigned)

Field	Type	Required	Description
`transactions`	`UnsignedTransaction[]`	Yes	One or more unsigned transactions.

Response Body (delegated)

Field	Type	Required	Description
`txHash`	`string`	Yes	Transaction hash of the delegated action.
`smartAccountAddress`	`string`	Yes	Smart account used for delegation.

Example Request

curl -X POST https://builder.ostiscan.xyz/v1/exchange/cancel \
  -H "Content-Type: application/json" \
  -H "X-Trader-Address: 0xYourWallet" \
  -d '{"cancels":[{"t":"limit","a":0,"i":1}]}'

Response (200, unsigned)

{
  "transactions": [
    { "to": "0x...", "data": "0x...", "value": "0", "from": "0xYourWallet" }
  ]
}

Response (200, delegated)

{
  "txHash": "0x...",
  "smartAccountAddress": "0x..."
}

Errors

See /docs/errors.

Exchange: Cancel

Alpha Version

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