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POST
/
v1
/
w3s
/
user
/
sign
/
message
Create a challenge to sign message
curl --request POST \
  --url https://api.circle.com/v1/w3s/user/sign/message \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-User-Token: <x-user-token>' \
  --data '
{
  "message": "I agree with this transfer",
  "walletId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5",
  "blockchain": "MATIC-AMOY",
  "walletAddress": "0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350",
  "encodedByHex": false,
  "memo": "Transfer USDC to Sam"
}
'
{
  "data": {
    "challengeId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5"
  }
}

Documentation Index

Fetch the complete documentation index at: https://developers.circle.com/llms.txt

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

Authorizations

​
Authorization
string
header
required

Circle's API Keys are formatted in the following structure "PREFIX:ID:SECRET". All three parts are required to make a successful request.

Headers

​
X-User-Token
string
required

Unique system generated JWT session token for specific user.

​
X-Request-Id
string<uuid>

Developer-provided identifier for this request, used for tracing requests in Wallets API logs and the Developer Console, and when communicating with Circle Support. Must be a UUID to appear in logs. Non-UUID values are accepted by the API but are ignored by logging and tracing systems.

A unique identifier, which can be helpful for identifying a request when communicating with Circle support.

Example:

"2adba88e-9d63-44bc-b975-9b6ae3440dde"

Body

application/json

Sign message for end user request

​
message
string
required

The user friendly message that needs to be signed. If it is a hex string, encodedByHex needs to be TRUE. The hex string should start with “0x” and have even length.

Example:

"I agree with this transfer"

​
walletId
string<uuid>

System-generated unique identifier of the resource.

Example:

"c4d1da72-111e-4d52-bdbf-2e74a2d803d5"

​
blockchain
enum<string>

The blockchain network that the resource is to be created on or is currently on.

Available options:
ETH,
ETH-SEPOLIA,
AVAX,
AVAX-FUJI,
MATIC,
MATIC-AMOY,
SOL,
SOL-DEVNET,
ARB,
ARB-SEPOLIA,
NEAR,
NEAR-TESTNET,
EVM,
EVM-TESTNET,
UNI,
UNI-SEPOLIA,
BASE,
BASE-SEPOLIA,
OP,
OP-SEPOLIA,
APTOS,
APTOS-TESTNET,
ARC-TESTNET,
MONAD,
MONAD-TESTNET
Example:

"MATIC-AMOY"

​
walletAddress
string

Blockchain generated unique identifier, associated with wallet (account), smart contract or other blockchain objects.

Example:

"0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350"

​
encodedByHex
boolean

Indicator of whether the input message is encoded by hex. If TRUE, then the message should be a hex string. By default, it is False.

Example:

false

​
memo
string

The human readable explanation for this sign action. Useful for presenting with extra information.

Example:

"Transfer USDC to Sam"

Response

Signature already exists

​
data
object
required