modify (gRPC) | Hyperliquid API Docs

Modify an existing order on Hyperliquid. Update price, size, or other parameters without cancelling.

Modify a single existing order's price, size, or other parameters. This allows updating an order without cancelling and re-submitting.

Sample Data

JSON

{
  "signature": {
    "r": "0xc99c77b2297349c8ab77d7a820a31e0d43646c9c938775b81b5aed101e89885f",
    "s": "0x881c0298616ca974aad375d044e5796ed719eac0b86cf2f1348e309f623231d",
    "v": 28
  },
  "action": {
    "type": "modify",
    "oid": 291708423670,
    "order": {
      "a": 191,
      "b": true,
      "p": "0.15042",
      "s": "6583",
      "r": false,
      "t": {
        "limit": {
          "tif": "Alo"
        }
      },
      "c": "0x55560089921887924531768146559426"
    }
  },
  "nonce": 1768146528890,
  "vaultAddress": "0x0bd00a003c3a494261789a9c87ff17f6e605e715"
}

View this transaction on Hypurrscan

Field Reference

Action Fields

Field	Type	Description
`type`	string	Always `"modify"`
`oid`	string	Order ID (or client order ID) to modify
`order`	object	New order parameters

Order Object Fields

Field	Type	Description
`a`	number	Asset index
`b`	boolean	Side: `true` for buy, `false` for sell
`p`	string	New limit price
`s`	string	New size
`r`	boolean	Reduce-only flag
`t`	object	Order type configuration
`c`	string	Client order ID

Optional Fields

Field	Type	Description
`vaultAddress`	string	Vault executing the modification
`expiresAfter`	number	Expiration timestamp

Use Cases

Order Update Tracking

Monitor how traders adjust their orders:

Python

def process_modify_action(action):
    oid = action.get('oid')
    order = action.get('order', {})
    new_price = order.get('p')
    new_size = order.get('s')

    print(f"Order {oid[:10]}... modified: price={new_price}, size={new_size}")

Market Maker Analysis

Track how frequently market makers update their quotes.

Price Improvement Detection

Monitor price improvements on existing orders.

order - Submit new orders
batchModify - Modify multiple orders atomically
cancel - Cancel orders

modify - Modify Single Order