> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.getunleash.io/api/create-segment/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.getunleash.io/_mcp/server.

# Create a new segment

POST https://app.unleash-instance.example.com/api/admin/segments
Content-Type: application/json

Creates a new segment using the payload provided

Reference: https://docs.getunleash.io/api/create-segment

## Authentication

- `Authorization` header (required) — API key needed to access this API
- `Authorization` header (bearer token, required) — API key needed to access this API, in Bearer token format

## Request

### Body (application/json)

This endpoint expects an upsertSegmentSchema.

- `name` (string, required) — The name of the segment
- `constraints` (list of constraintSchema, required) — The list of constraints that make up this segment
- `description` (string, optional, nullable) — A description of what the segment is for
- `project` (string, optional, nullable) — The project the segment belongs to if any.

## Response

### 201

The resource was successfully created.

- `id` (integer, required) — The ID of this segment
- `name` (string, required) — The name of this segment
- `constraints` (list of constraintSchema, required) — The list of constraints that are used in this segment
- `createdAt` (string, required) — When the segment was created
- `description` (string, optional, nullable) — The description for this segment
- `usedInFeatures` (integer, optional, nullable) — The number of feature flags that use this segment. The number also includes the any flags with pending change requests that would add this segment.
- `usedInProjects` (integer, optional, nullable) — The number of projects that use this segment. The number includes any projects with pending change requests that would add this segment.
- `project` (string, optional, nullable) — The project the segment belongs to. Only present if the segment is a project-specific segment.
- `createdBy` (string, optional, nullable) — The creator's email or username

## Errors

### 400 Bad Request Error

The request data does not match what we expect.

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

### 401 Unauthorized Error

Authorization information is missing or invalid. Provide a valid API token as the `authorization` header, e.g. `authorization:*.*.my-admin-token`.

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

### 403 Forbidden Error

The provided user credentials are valid, but the user does not have the necessary permissions to perform this operation

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

### 409 Conflict Error

The provided resource can not be created or updated because it would conflict with the current state of the resource or with an already existing resource, respectively.

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

### 415 Unsupported Media Type Error

The operation does not support request payloads of the provided type. Please ensure that you're using one of the listed payload types and that you have specified the right content type in the "content-type" header.

- `id` (string, optional) — The ID of the error instance
- `name` (string, optional) — The name of the error kind
- `message` (string, optional) — A description of what went wrong.

## Types

### constraintSchema

A strategy constraint. For more information, refer to [the strategy constraint reference documentation](https://docs.getunleash.io/concepts/activation-strategies#constraints)

- `contextName` (string, required) — The name of the context field that this constraint should apply to.
- `operator` (enum, required) — The operator to use when evaluating this constraint. For more information about the various operators, refer to [the strategy constraint operator documentation](https://docs.getunleash.io/concepts/activation-strategies#constraint-operators).
  - Allowed values: `NOT_IN`, `IN`, `STR_ENDS_WITH`, `STR_STARTS_WITH`, `STR_CONTAINS`, `NUM_EQ`, `NUM_GT`, `NUM_GTE`, `NUM_LT`, `NUM_LTE`, `DATE_AFTER`, `DATE_BEFORE`, `SEMVER_EQ`, `SEMVER_GT`, `SEMVER_LT`, `SEMVER_GTE`, `SEMVER_LTE`, `REGEX`
- `caseInsensitive` (boolean, optional, default: false) — Whether the operator should be case sensitive or not. Defaults to `false` (being case sensitive).
- `inverted` (boolean, optional, default: false) — Whether the result should be negated or not. If `true`, will turn a `true` result into a `false` result and vice versa.
- `values` (list of string, optional) — The context values that should be used for constraint evaluation. Use this property instead of `value` for properties that accept multiple values.
- `value` (string, optional) — The context value that should be used for constraint evaluation. Use this property instead of `values` for properties that only accept single values.

## Examples

**Request**

```json
{
  "name": "beta-users",
  "constraints": [
    {
      "contextName": "appName",
      "operator": "IN"
    }
  ]
}
```

**Response**

```json
{
  "id": 2,
  "name": "ios-users",
  "constraints": [
    {
      "contextName": "appName",
      "operator": "IN",
      "caseInsensitive": false,
      "inverted": false,
      "values": [
        "my-app",
        "my-other-app"
      ],
      "value": "my-app"
    }
  ],
  "createdAt": "2023-04-12T11:13:31.960Z",
  "description": "IOS users segment",
  "usedInFeatures": 3,
  "usedInProjects": 2,
  "project": "red-vista",
  "createdBy": "someone@example.com"
}
```

**SDK Code**

```python
import requests

url = "https://app.unleash-instance.example.com/api/admin/segments"

payload = {
    "name": "beta-users",
    "constraints": [
        {
            "contextName": "appName",
            "operator": "IN"
        }
    ]
}
headers = {
    "Authorization": "<apiKey>",
    "Content-Type": "application/json"
}

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

print(response.json())
```

```javascript
const url = 'https://app.unleash-instance.example.com/api/admin/segments';
const options = {
  method: 'POST',
  headers: {Authorization: '<apiKey>', 'Content-Type': 'application/json'},
  body: '{"name":"beta-users","constraints":[{"contextName":"appName","operator":"IN"}]}'
};

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://app.unleash-instance.example.com/api/admin/segments"

	payload := strings.NewReader("{\n  \"name\": \"beta-users\",\n  \"constraints\": [\n    {\n      \"contextName\": \"appName\",\n      \"operator\": \"IN\"\n    }\n  ]\n}")

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

	req.Header.Add("Authorization", "<apiKey>")
	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://app.unleash-instance.example.com/api/admin/segments")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = '<apiKey>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"name\": \"beta-users\",\n  \"constraints\": [\n    {\n      \"contextName\": \"appName\",\n      \"operator\": \"IN\"\n    }\n  ]\n}"

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://app.unleash-instance.example.com/api/admin/segments")
  .header("Authorization", "<apiKey>")
  .header("Content-Type", "application/json")
  .body("{\n  \"name\": \"beta-users\",\n  \"constraints\": [\n    {\n      \"contextName\": \"appName\",\n      \"operator\": \"IN\"\n    }\n  ]\n}")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://app.unleash-instance.example.com/api/admin/segments', [
  'body' => '{
  "name": "beta-users",
  "constraints": [
    {
      "contextName": "appName",
      "operator": "IN"
    }
  ]
}',
  'headers' => [
    'Authorization' => '<apiKey>',
    'Content-Type' => 'application/json',
  ],
]);

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

```csharp
using RestSharp;

var client = new RestClient("https://app.unleash-instance.example.com/api/admin/segments");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "<apiKey>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"name\": \"beta-users\",\n  \"constraints\": [\n    {\n      \"contextName\": \"appName\",\n      \"operator\": \"IN\"\n    }\n  ]\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "<apiKey>",
  "Content-Type": "application/json"
]
let parameters = [
  "name": "beta-users",
  "constraints": [
    [
      "contextName": "appName",
      "operator": "IN"
    ]
  ]
] as [String : Any]

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

let request = NSMutableURLRequest(url: NSURL(string: "https://app.unleash-instance.example.com/api/admin/segments")! 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()
```