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POST
/
custodians
/
me
/
clients
/
{clientId}
/
chains
/
{chain}
/
assets
/
send
/
build-transaction
Build a transaction
curl --request POST \
  --url https://api.portalhq.io/api/v3/custodians/me/clients/{clientId}/chains/{chain}/assets/send/build-transaction \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "to": "0xdFd8302f44727A6348F702fF7B594f127dE3A902",
  "token": "USDC",
  "amount": "0.01"
}
'
{
  "transaction": {
    "from": "0x21d8d1d2d9907c051670d8c9a80bd2192d273f8d",
    "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    "data": "0xa9059cbb000000000000000000000000dfd8302f44727a6348f702ff7b594f127de3a9020000000000000000000000000000000000000000000000000000000000002710"
  },
  "metadata": {
    "rawAmount": "10000",
    "formattedAmount": "0.01",
    "tokenDecimals": 6,
    "tokenAddress": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48"
  }
}

Authorizations

​
Authorization
string
header
required

Portal API Key (Custodian API Key). Pass as a Bearer token in the Authorization header.

Path Parameters

​
clientId
string
required

The unique identifier of the client.

​
chain
string
required

The blockchain chain identifier. Use either a friendly name or CAIP-2 format. When using CAIP-2 format in URLs, ensure the colon (:) is URI-encoded as %3A.

Supported chains:

  • ethereum (eip155:1)
  • sepolia (eip155:11155111)
  • base (eip155:8453)
  • base-sepolia (eip155:84532)
  • polygon (eip155:137)
  • polygon-amoy (eip155:80002)
  • celo (eip155:42220)
  • celo-alfajores (eip155:44787)
  • monad-testnet (eip155:10143)
  • solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp)
  • solana-devnet (solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1)
  • tron (tron:mainnet)
  • tron-nile (tron:nile)
  • tron-shasta (tron:shasta)
  • stellar (stellar:pubnet)
  • stellar-testnet (stellar:testnet)
  • bitcoin-segwit (bip122:000000000019d6689c085ae165831e93-p2wpkh)
  • bitcoin-segwit-testnet (bip122:000000000933ea01ad0ee984209779ba-p2wpkh)

Body

application/json
​
to
string
required

The recipient's wallet address.

​
token
string
required

The token symbol (e.g. USDC) or contract/mint address.

​
amount
string
required

The amount to transfer in the token's primary denomination. Must be greater than zero.

Response

Unsigned transaction built successfully. The response structure depends on the chain type.

​
transaction
object
​
metadata
object