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POST
/
v1
/
sign
Sign a transaction or message by chain
curl --request POST \
  --url https://mpc-client.portalhq.io/v1/sign \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "share": "eyJjbG...",
  "method": "eth_sendTransaction",
  "params": {
    "value": "0x01",
    "from": "",
    "to": "0xdFd8302f44727A6348F702fF7B594f127dE3A902",
    "data": ""
  },
  "rpcUrl": "https://api.portalhq.io/rpc/v1/eip155/10143",
  "chainId": "eip155:10143"
}
'
{
  "data": "0xf7a6a07fa599db56fca50fa1202670b59054e7ed452ea57b3f5b43148b8bdb165beb3a4b0fd532162a1f0fd475de1a9ecd07c95186f7a0856ce1bffa45e3acc91b"
}

Documentation Index

Fetch the complete documentation index at: https://docs.portalhq.io/llms.txt

Use this file to discover all available pages before exploring further.

Authorizations

​
Authorization
string
header
required

Client API Key or Client Session Token

Headers

​
Idempotency-Key
string

A caller-provided key used for safe retries. Behavior depends on the endpoint:

  • POST /v1/presign/{curve} with managed: true — retrying a completed request with the same key returns the same {id, expiresAt} (200). If the original attempt is still in progress, the retry returns 409 with a Retry-After header; if the original attempt failed before completing, it returns 409 without Retry-After (caller should retry with a new key). Reusing a key after the wallet's signing share has changed (for example, after a reshare or recovery) returns 422.
  • POST /v1/sign — only honored for broadcast methods (for example eth_sendTransaction, sol_signAndSendTransaction). Supplying the header with a non-broadcast method returns 400. For broadcast methods, retrying a completed request returns 409 (IDEMPOTENT_REQUEST_ALREADY_COMPLETED), and reuse with a different payload returns 422. On 409, the response body does not include the original signing result — the header prevents double-execution, it does not replay the prior response.
  • POST /v1/assets/send — retrying a completed request returns 409 (IDEMPOTENT_REQUEST_ALREADY_COMPLETED), and reuse with a different payload returns 422. On 409, the response body does not include the original transactionHash — the header prevents double-submission, it does not replay the prior response.

Client-stored presignature creation does not currently honor this header.

Body

application/json

Request body for signing a transaction or message by chain.

​
method
string
required

The signer RPC method (e.g. personal_sign, eth_sendTransaction, sol_signAndSendTransaction).

​
params
required

The parameters for the RPC method as a JSON object or array (e.g. {"value": "0x01", "from": "", "to": "0x...", "data": ""}).

​
share
string
required

The MPC share for the relevant curve.

​
chainId
string
required

The blockchain network as a CAIP-2 chain ID (e.g. eip155:10143).

​
to
string
required

The recipient's address.

​
rpcUrl
string
required

The node provider RPC URL.

​
metadataStr
string

Optional metadata string for the transaction.

​
sponsorGas
boolean

Set to false to opt out of gas sponsorship for Account Abstraction clients. Defaults to true when omitted.

​
presignature
string

The data value from a client-stored presign response. Omit for standard (non-presigned) signing. Mutually exclusive with presignatureId.

​
presignatureId
string

The id value from a Portal-managed presign response. Omit for standard (non-presigned) signing. Mutually exclusive with presignature.

Response

Signed successfully

Response containing the signed data.

​
data
string
required

The signed data as a hex string.