# Customer Creation

{% hint style="info" %}
This step assumes you have successfully authenticated your API credentials using [Authentication](/developer-guides/step-by-step-guide/authentication.md) and have followed [Request Signatures](/developer-guides/api-integration/request-signatures.md) and [Idempotency](/developer-guides/api-integration/idempotency.md) guides to configure your requests
{% endhint %}

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.

{% openapi src="/files/ZuFqAH96VVGgwQAJ2vzc" path="/customers" method="post" expanded="true" %}
[offblocks-api-spec\_master\_api.yaml](https://1545901005-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTToCQFhAYRMgObGgbSjC%2Fuploads%2FV89o79d3urx40FHQswwW%2Foffblocks-api-spec_master_api.yaml?alt=media\&token=762e0468-4f4f-407e-9281-df4ee98be768)
{% endopenapi %}

Specified `chainId` is expected to follow the convention outlined in [Blockchain Identifiers](/developer-guides/api-integration/blockchain-identifiers.md#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:

```json
{
  "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:

{% code overflow="wrap" %}

```json
{
    "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"
}
```

{% endcode %}

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](/developer-guides/api-integration/sign-in-with-x.md) 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.

{% openapi src="/files/ZuFqAH96VVGgwQAJ2vzc" path="/customers/{customerId}/challenge/sign" method="post" expanded="true" %}
[offblocks-api-spec\_master\_api.yaml](https://1545901005-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTToCQFhAYRMgObGgbSjC%2Fuploads%2FV89o79d3urx40FHQswwW%2Foffblocks-api-spec_master_api.yaml?alt=media\&token=762e0468-4f4f-407e-9281-df4ee98be768)
{% endopenapi %}

{% code overflow="wrap" %}

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

{% endcode %}

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.

{% openapi src="/files/ZuFqAH96VVGgwQAJ2vzc" path="/customers/{customerId}/challenge" method="get" expanded="true" %}
[offblocks-api-spec\_master\_api.yaml](https://1545901005-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTToCQFhAYRMgObGgbSjC%2Fuploads%2FV89o79d3urx40FHQswwW%2Foffblocks-api-spec_master_api.yaml?alt=media\&token=762e0468-4f4f-407e-9281-df4ee98be768)
{% endopenapi %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.offblocks.xyz/developer-guides/step-by-step-guide/customer-creation.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.