4️⃣Customer Creation

This step assumes you have successfully authenticated your API credentials using Authentication and have followed Request Signatures and Idempotency guides to configure your requests

Now that you can make authenticated requests to the API, you are officially ready to onboard new customers with our platform. To do so, you need to use /customers POST request.

Create new customer

post

Creates new customer and generates a cryptographic challenge to verify ownership of blockchain account

Authorizations

Header parameters

Signaturestringrequired

HTTP message signature

Signature-Inputstringrequired

HTTP message signature input

Idempotency-Keystring · uuidrequired

Idempotency key (UUID)

Content-Digeststringrequired

Content digest

Body

chainIdstringrequired

Unique customer ID in a form of a valid on-chain address. This would normally correspond to customer's EOA wallet address

Example: eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb

externalIdstringrequired

Unique customer ID in a form of an external identifier. This would normally correspond to customer's ID in your system

Responses

application/json

cURL

JavaScript

Python

HTTP

cURL

curl -L \
  --request POST \
  --url 'https://api.offblocks.xyz/v1/customers' \
  --header 'Authorization: Bearer JWT' \
  --header 'Signature: text' \
  --header 'Signature-Input: text' \
  --header 'Idempotency-Key: 123e4567-e89b-12d3-a456-426614174000' \
  --header 'Content-Digest: text' \
  --header 'Content-Type: application/json' \
  --data '{
    "chainId": "eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb",
    "externalId": "text"
  }'

201

400

401

409

500

201

{
  "id": "123e4567-e89b-12d3-a456-426614174000",
  "externalId": "text",
  "chainId": "eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb",
  "status": "initiating",
  "createdAt": "2025-04-03T07:58:49.718Z",
  "updatedAt": "2025-04-03T07:58:49.718Z",
  "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0="
}

Successful operation

Specified chainId is expected to follow the convention outlined in Account Identifier. For example, in order to onboard a customer using zkSync Era wallet with address 0x22227A31dd842196A246d8f3b775998560eAa61d on Goerli Testnet, you can submit a following request:

{
  "chainId": "eip155:280:0x22227A31dd842196A246d8f3b775998560eAa61d",
  "externalId": "27c9aa3b-f12d-43b9-8e91-5264ccc998de"
}

If a customer with specified chainId and externalId is not onboarded in our system yet, you will receive a response with status 201 (Created) which looks similar to the following:

{
    "chainId": "eip155:280:0x22227A31dd842196A246d8f3b775998560eAa61d",
    "challenge": "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",
    "createdAt": "2024-01-12T14:53:02.65345725Z",
    "externalId": "27c9aa3b-f12d-43b9-8e91-5264ccc998de",
    "id": "04c5851c-4386-5bd9-9f89-08312f8aee3a",
    "status": "initiating",
    "updatedAt": "2024-01-12T14:53:02.65345725Z"
}

If everything went well, you will receive a customer challenge to sign as a base64 encoded string. This is required to proceed to verification stage. Please, follow Sign in With X guide for more details on signing a customer challenge.

In order to submit a signed challenge, use a POST request to /customers/{customerId}/challenge/sign endpoint.

Sign previously issued customer challenge

post

Signs previously issued challenge to verify customer's ownership of their blockchain account

Authorizations

Path parameters

customerIdstring · uuidrequired

Unique customer ID

Header parameters

Signaturestringrequired

HTTP message signature

Signature-Inputstringrequired

HTTP message signature input

Idempotency-Keystring · uuidrequired

Idempotency key (UUID)

Content-Digeststringrequired

Content digest

Body

ownerIdstringrequired

Unique signer account ID in a form of a valid on-chain address

Example: eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb

challengestring · byterequired

Original base64 encoded challenge provided by this API for owner to sign

Example: LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=

signaturestring · byterequired

Base64 encoded signature

Example: IfvwaW1eCqLvQaK0/7YjvK8HBGHWHPclHHQWH4L+w6Q3CFS8CjSzq0h8G8AhzTGMc0xRrik3TyvrDm8t1JtL9Bw=

Responses

cURL

JavaScript

Python

HTTP

cURL

curl -L \
  --request POST \
  --url 'https://api.offblocks.xyz/v1/customers/{customerId}/challenge/sign' \
  --header 'Authorization: Bearer JWT' \
  --header 'Signature: text' \
  --header 'Signature-Input: text' \
  --header 'Idempotency-Key: 123e4567-e89b-12d3-a456-426614174000' \
  --header 'Content-Digest: text' \
  --header 'Content-Type: application/json' \
  --data '{
    "ownerId": "eip155:1:0xab16a96D359eC26a11e2C2b3d8f8B8942d5Bfcdb",
    "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0=",
    "signature": "IfvwaW1eCqLvQaK0/7YjvK8HBGHWHPclHHQWH4L+w6Q3CFS8CjSzq0h8G8AhzTGMc0xRrik3TyvrDm8t1JtL9Bw="
  }'

204

400

401

404

409

500

204

No body

Successful operation

{
  "ownerId": "eip155:280:0x43158f45b5EbD7b1179130131DF00393928C2691",
  "challenge": "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",
  "signature": "MHg4M2IxM2RhYjE2MjI3MjAxMWQzMzQ4NDFkZjE5NTQ1MjUwNDI1NjczMjhhZDdjMDVjOTYyYjAwNWVlZDg3MGI2NDhjMjA0ZjBiZmZjZjUyYjM3NTE0MGIwYzg0OTA4ZTQ2MzMyNWIxZGZlNWJiYjAzMjU5NzYyNDgyODM0YWYzNzFi"
}

Please, not that the signature also must be a base64 encoded string. If signature is verified, you will receive an empty response with status code 204 (No Content).

If, for any reason, the original challenge is lost or cannot be signed immediately, you can fetch it again using a dedicated endpoint. If we encounter an error during signature validation via /sign endpoint, a new challenge will be issued for you to retrieve.

We enforce a 1 hour expiration window via our API for all issued challenges for security purposes. If a challenge hasn't been signed within 1 hour from issue, we will generate a new one and make it available through this endpoint.

Retrieve customer challenge

get

Retrieves challenge to verify customer's ownership of their blockchain account

Authorizations

Path parameters

customerIdstring · uuidrequired

Unique customer ID

Header parameters

Signaturestringrequired

HTTP message signature

Signature-Inputstringrequired

HTTP message signature input

Responses

application/json

cURL

JavaScript

Python

HTTP

cURL

curl -L \
  --url 'https://api.offblocks.xyz/v1/customers/{customerId}/challenge' \
  --header 'Authorization: Bearer JWT' \
  --header 'Signature: text' \
  --header 'Signature-Input: text'

200

400

401

404

500

200

{
  "challenge": "LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUZZd0VBWUhLb1pJemowQ0FRWUZLNEVFQUFvRFFnQUUzTEw1RldmVFgvL3BJaXNEL0xneFVIT2lxdlFTSUVWTgpGekloOTdLZXBlWk1iZVZsUGd1akZ4Yk5MN2x1ZVhRQnBpUWUzNmZLN0xSbXZNNHdEaWZFTkE9PQotLS0tLUVORCBQVUJMSUMgS0VZLS0tLS0="
}

Successful operation