> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.trygrant.com/api-reference/grant-events-api/customers/update/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.trygrant.com/_mcp/server.

# Update a customer

POST https://api.trygrant.com/v1/customers/{id}
Content-Type: application/json

Updates an existing customer. Only provided fields are changed.

Reference: https://docs.trygrant.com/api-reference/grant-events-api/customers/update

## Authentication

- `Authorization` header (bearer token, required) — API key obtained from the Grant dashboard

## Servers

- `https://api.trygrant.com` (Production, default)
- `http://localhost:8787` (Local development)

## Request

### Path parameters

- `id` (string, required)

### Body (application/json)

This endpoint expects an UpdateCustomerRequest.

- `name` (string, optional) — Business or display name
- `first_name` (string, optional) — Contact first name
- `last_name` (string, optional) — Contact last name
- `email` (string, optional) — Primary email address
- `phone` (string, optional) — Phone number
- `url` (string, optional) — Website URL
- `external_id` (string, optional) — Your internal identifier for this customer
- `billing_address` (UpdateCustomerRequestBillingAddress, optional) — Billing address
- `shipping_address` (UpdateCustomerRequestShippingAddress, optional) — Shipping address

## Response

### 200

Customer updated

- `success` (boolean, required)
- `customer` (Customer, required)
- `request_id` (string, required)

## Errors

### 400 Bad Request Error

Invalid request

- `success` (boolean, required)
- `error` (ErrorResponseError, required)
- `request_id` (string, optional) — Request ID for tracing

### 401 Unauthorized Error

Unauthorized

- `success` (boolean, required)
- `error` (ErrorResponseError, required)
- `request_id` (string, optional) — Request ID for tracing

### 404 Not Found Error

Customer not found

- `success` (boolean, required)
- `error` (ErrorResponseError, required)
- `request_id` (string, optional) — Request ID for tracing

### 500 Internal Server Error

Internal server error

- `success` (boolean, required)
- `error` (ErrorResponseError, required)
- `request_id` (string, optional) — Request ID for tracing

## Types

### UpdateCustomerRequestBillingAddress

Billing address

- `country` (string, optional) — Two-letter ISO country code
- `state` (string, optional) — State or province
- `city` (string, optional) — City name
- `street` (string, optional) — Street address line 1
- `street2` (string, optional) — Street address line 2
- `zip` (string, optional) — Postal / ZIP code

### UpdateCustomerRequestShippingAddress

Shipping address

- `country` (string, optional) — Two-letter ISO country code
- `state` (string, optional) — State or province
- `city` (string, optional) — City name
- `street` (string, optional) — Street address line 1
- `street2` (string, optional) — Street address line 2
- `zip` (string, optional) — Postal / ZIP code

### Customer

- `id` (string, required)
- `name` (string, required, nullable)
- `first_name` (string, required, nullable)
- `last_name` (string, required, nullable)
- `email` (string, required, nullable)
- `phone` (string, required, nullable)
- `url` (string, required, nullable)
- `external_id` (string, required, nullable)
- `billing_address` (CustomerBillingAddress, required, nullable) — Billing address
- `shipping_address` (CustomerShippingAddress, required, nullable) — Shipping address
- `created_at` (string, required) — ISO 8601 creation timestamp
- `updated_at` (string, required) — ISO 8601 last-updated timestamp

### ErrorResponseError

- `code` (string, required)
- `message` (string, required)
- `details` (any, optional)

### CustomerBillingAddress

Billing address

- `country` (string, optional) — Two-letter ISO country code
- `state` (string, optional) — State or province
- `city` (string, optional) — City name
- `street` (string, optional) — Street address line 1
- `street2` (string, optional) — Street address line 2
- `zip` (string, optional) — Postal / ZIP code

### CustomerShippingAddress

Shipping address

- `country` (string, optional) — Two-letter ISO country code
- `state` (string, optional) — State or province
- `city` (string, optional) — City name
- `street` (string, optional) — Street address line 1
- `street2` (string, optional) — Street address line 2
- `zip` (string, optional) — Postal / ZIP code

## Examples

**Request**

```json
{}
```

**Response**

```json
{
  "success": true,
  "customer": {
    "id": "cm5x9z8nv0000h85r7l9p2k1m",
    "name": "Acme Corp",
    "first_name": "Jane",
    "last_name": "Doe",
    "email": "jane@acme.com",
    "phone": "+14155551234",
    "url": "https://acme.com",
    "external_id": "cust_ext_123",
    "billing_address": {
      "country": "US",
      "state": "CA",
      "city": "San Francisco",
      "street": "123 Main St",
      "street2": "Suite 100",
      "zip": "94105"
    },
    "shipping_address": {
      "country": "US",
      "state": "CA",
      "city": "San Francisco",
      "street": "123 Main St",
      "street2": "Suite 100",
      "zip": "94105"
    },
    "created_at": "2024-01-15T10:30:00.000Z",
    "updated_at": "2024-01-15T10:30:00.000Z"
  },
  "request_id": "req_abc123"
}
```

**SDK Code**

```python
import requests

url = "https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m"

payload = {}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{}'
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m"

	payload := strings.NewReader("{}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{}"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{}")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m', [
  'body' => '{}',
  'headers' => [
    'Authorization' => 'Bearer <token>',
    'Content-Type' => 'application/json',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = [] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.trygrant.com/v1/customers/cm5x9z8nv0000h85r7l9p2k1m")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```

> API documentation for Grant — billing infrastructure for usage-based pricing