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Websocket API

The Standard Relayer API also exposes a websocket server at the root endpoint.

Ethereum Mainnetwss://

The server will allow you to subscribe to 0x order updates, and will push updates whenever the "fillability" of an order changes. In practice, this will happen whenever a new order is added, an order is cancelled, or an order is filled. At the moment, the update message will not specify the exact reason for the update.

All messages (both request, and response) adhere to the format below:

typeThe type of message being sent. Only "subscribe" is supported for now
channelThe topic of the messaging. Only "orders" is supported for now.
requestIdA string uuid that will be sent back by the server in response messages so the client can appropriately respond when multiple subscriptions are made.
payload(Optional) A JSON object documented below, that contains the body of the message.


makerToken(Optional) Filter orders by the address of the ERC20 token the maker is selling. Example 0xe41d2489571d322189246dafa5ebde1f4699f498
takerToken(Optional) Filter orders by the address of the ERC20 token the taker is selling. Example 0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2


A list consisting of signed orders with metaData.

orderRaw signed orders.
metaDataObject where optional meta-data will be included, such as the orderHash and remainingFillableTakerAmount.


Subscribe to All Order Updates


"type": "subscribe",
"channel": "orders",
"requestId": "123e4567-e89b-12d3-a456-426655440000"


"type": "update",
"channel": "orders",
"payload": [
"order": {
"chainId": 1,
"verifyingContract": "0xdef1c0ded9bec7f1a1670819833240f027b25eff",
"makerToken": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
"takerToken": "0xe41d2489571d322189246dafa5ebde1f4699f498",
"makerAmount": "1",
"takerAmount": "1000000000000000",
"takerTokenFeeAmount": "0",
"maker": "0x56eb0ad2dc746540fab5c02478b31e2aa9ddc38c",
"taker": "0x0000000000000000000000000000000000000000",
"sender": "0x0000000000000000000000000000000000000000",
"feeRecipient": "0x0000000000000000000000000000000000000000",
"pool": "0x0000000000000000000000000000000000000000000000000000000000000000",
"expiry": "1614962196",
"salt": "12213086377898595950156985364849399280012820680806192474044093697918905947103",
"signature": {
"signatureType": 3,
"v": 28,
"r": "0x828110c66e0b5435ad2b2a4479f2ca5ea6afaf2846a7d5218aeb4e7f2519ce7b",
"s": "0x06360f6d55d86006c090855f5467925707788bdfb4bfb7aae7304f0504c93ba0"
"metaData": {
"orderHash": "0xa3aeb3b1aed8438c0398ba070bf4f365378ef74e4fc966f09df87854484b0012",
"remainingFillableTakerAmount": "1000000000000000",
"state": "ADDED"
"requestId": "123e4567-e89b-12d3-a456-426655440000"