> Calendly developer docs. For page Markdown, append .md to any URL.
> Index: https://developer.calendly.com/llms.txt
> API catalog: https://developer.calendly.com/.well-known/api-catalog
> OpenAPI: https://developer.calendly.com/openapi/calendly-api.yaml
> OAuth authorization server: https://calendly.com/.well-known/oauth-authorization-server
> MCP protected resource: https://mcp.calendly.com/.well-known/oauth-protected-resource
> Scheduling MCP endpoint: https://mcp.calendly.com
> Docs search MCP: https://developer.calendly.com/_mcp/server

# List Contact Custom Field Definitions

GET https://api.calendly.com/contacts/custom_field_definitions

Returns all custom field definitions available to the authenticated user or organization.

> `contacts:read`

Reference: https://developer.calendly.com/api-docs/calendly-api/contacts/list-contact-custom-field-definitions

## Authentication

- `Authorization` header (bearer token, required) — OAuth 2.0
- `Authorization` header (bearer token, required) — Personal Access Token

## Response

### 200

OK

- `collection` (list of ContactCustomFieldDefinition, required)

## Errors

### 400 Bad Request Error

Request is not valid

- `title` (enum, required)
  - Allowed values: `Internal Server Error`
- `message` (enum, required)
  - Allowed values: `The server encountered an unexpected condition that prevented it from fulfilling the request.`
- `details` (list of ErrorResponseDetailsItem, optional)

### 401 Unauthorized Error

Cannot authenticate caller

- `title` (enum, required)
  - Allowed values: `Internal Server Error`
- `message` (enum, required)
  - Allowed values: `The server encountered an unexpected condition that prevented it from fulfilling the request.`
- `details` (list of ErrorResponseDetailsItem, optional)

### 403 Forbidden Error

Permission Denied or insufficient scope

- `List-contact-custom-field-definitionsRequestForbiddenError`

### 404 Not Found Error

Requested resource not found

- `title` (enum, required)
  - Allowed values: `Internal Server Error`
- `message` (enum, required)
  - Allowed values: `The server encountered an unexpected condition that prevented it from fulfilling the request.`
- `details` (list of ErrorResponseDetailsItem, optional)

### 500 Internal Server Error

An error has occurred on the server

- `title` (enum, required)
  - Allowed values: `Internal Server Error`
- `message` (enum, required)
  - Allowed values: `The server encountered an unexpected condition that prevented it from fulfilling the request.`
- `details` (list of ErrorResponseDetailsItem, optional)

## Types

### ContactCustomFieldDefinition

A custom field definition describes the schema for a field that can be applied to Contacts.

- `uri` (string, required) — Canonical URI of the custom field definition.
- `label` (string, required) — User-facing display name.
- `field_type` (enum, required) — Calendly custom field kind, which determines both input behavior and the expected value type.
  - Allowed values: `text`, `number`, `currency`, `tags`, `date`, `single_select`, `invitee_question`
- `created_at` (string, required) — Creation timestamp.
- `updated_at` (string, required) — Last update timestamp.
- `options` (list of ContactCustomFieldOption, optional) — Allowed options for `single_select` fields. Returned in configured display order.
- `currency` (string, optional) — ISO currency code for currency fields, if applicable.
- `source` (ContactCustomFieldSource, optional) — Source metadata for system-generated fields. Present when `field_type` is `invitee_question`.

### ErrorResponseDetailsItem

- `message` (string, required)
- `parameter` (string, optional)
- `code` (string, optional)

### ContactsError

Permission Denied

- `title` (enum, required)
  - Allowed values: `Permission Denied`
- `message` (enum, required)
  - Allowed values: `Please upgrade your Calendly account to Enterprise.`, `You do not have permission to access this resource.`, `Please upgrade to a paid Calendly account.`, `Contact creation is not available. Required features are not enabled for your account.`

### InsufficientScopeError

Caller does not have required oauth scopes

- `title` (enum, required)
  - Allowed values: `Insufficient scope`
- `message` (enum, required)
  - Allowed values: `This operation requires the scopes listed in the 'required_scopes' array.`
- `required_scopes` (list of string, required)

### ContactCustomFieldOption

- `uuid` (string, required) — Unique identifier for the option. Used in Contact `custom_fields` entries when `field_type` is `single_select`.
- `label` (string, required) — User-facing display label for the option.
- `is_active` (boolean, required) — Whether the option is active and selectable.
- `color` (string, optional) — Display color for the option.

### ContactCustomFieldSource

Source metadata for system-generated fields, such as invitee questions.

- `type` (enum, required)
  - Allowed values: `event_type_invitee_question`
- `event_type_uri` (string, optional)
- `question` (string, optional)

## Examples

### Invitee question definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Meeting prep notes",
      "field_type": "invitee_question",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z",
      "source": {
        "type": "event_type_invitee_question",
        "event_type_uri": "https://api.calendly.com/event_types/AAAAAAAAAAAAAAAA",
        "question": "Please share anything that will help prepare for our meeting."
      }
    }
  ]
}
```

**SDK Code**

```python Invitee question definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Invitee question definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Invitee question definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

```ruby Invitee question definition
require 'uri'
require 'net/http'

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

```java Invitee question definition
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Invitee question definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Invitee question definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Currency definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Currency Field Money",
      "field_type": "currency",
      "created_at": "2026-05-19T16:51:05.873Z",
      "updated_at": "2026-07-08T11:26:52.757Z",
      "currency": "USD"
    }
  ]
}
```

**SDK Code**

```python Currency definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Currency definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Currency definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

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

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

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

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Currency definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Currency definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Single select definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Lead source",
      "field_type": "single_select",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z",
      "options": [
        {
          "uuid": "DDDDDDDDDDDDDDDD",
          "label": "Website",
          "is_active": true,
          "color": "blue-light"
        },
        {
          "uuid": "EEEEEEEEEEEEEEEE",
          "label": "Referral",
          "is_active": true,
          "color": "purple-light"
        }
      ]
    }
  ]
}
```

**SDK Code**

```python Single select definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Single select definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Single select definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

```ruby Single select definition
require 'uri'
require 'net/http'

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

```java Single select definition
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Single select definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Single select definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Text definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Notes",
      "field_type": "text",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z"
    }
  ]
}
```

**SDK Code**

```python Text definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Text definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Text definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

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

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

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

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Text definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Text definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Number definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Deal size",
      "field_type": "number",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z"
    }
  ]
}
```

**SDK Code**

```python Number definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Number definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Number definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

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

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

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

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Number definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Number definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Tags definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Tags",
      "field_type": "tags",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z"
    }
  ]
}
```

**SDK Code**

```python Tags definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Tags definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Tags definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

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

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

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

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Tags definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Tags definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

### Date definition

**Response**

```json
{
  "collection": [
    {
      "uri": "https://api.calendly.com/contacts/custom_field_definitions/CCCCCCCCCCCCCCCC",
      "label": "Renewal date",
      "field_type": "date",
      "created_at": "2026-06-03T20:52:43Z",
      "updated_at": "2026-06-03T20:52:43Z"
    }
  ]
}
```

**SDK Code**

```python Date definition
import requests

url = "https://api.calendly.com/contacts/custom_field_definitions"

headers = {"Authorization": "Bearer <token>"}

response = requests.get(url, headers=headers)

print(response.json())
```

```javascript Date definition
const url = 'https://api.calendly.com/contacts/custom_field_definitions';
const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

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

```go Date definition
package main

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

func main() {

	url := "https://api.calendly.com/contacts/custom_field_definitions"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

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

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

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

}
```

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

url = URI("https://api.calendly.com/contacts/custom_field_definitions")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Bearer <token>'

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

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

HttpResponse<String> response = Unirest.get("https://api.calendly.com/contacts/custom_field_definitions")
  .header("Authorization", "Bearer <token>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://api.calendly.com/contacts/custom_field_definitions', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

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

```csharp Date definition
using RestSharp;

var client = new RestClient("https://api.calendly.com/contacts/custom_field_definitions");
var request = new RestRequest(Method.GET);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Date definition
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.calendly.com/contacts/custom_field_definitions")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```