---
title: create-a-flag
product: vercel
url: /docs/rest-api/feature-flags/create-a-flag
canonical_url: "https://vercel.com/docs/rest-api/feature-flags/create-a-flag"
last_updated: 2026-09-14
type: reference
prerequisites:
  []
related:
  - /docs/rest-api
summary: Learn about create-a-flag on Vercel.
install_vercel_plugin: npx plugins add vercel/vercel-plugin
---

# Create a flag

```http
PUT /v1/projects/{projectIdOrName}/feature-flags/flags
```

Create a new feature flag for a project. The flag must have a unique slug within the project and specify its kind (boolean, string, number, or json).

## Authentication

**bearerToken**: HTTP bearer

## Path parameters

| Name | Type | Required | Description |
|---|---|---|---|
| `projectIdOrName` | string | Yes | The project id or name |


## Query parameters

| Name | Type | Required | Description |
|---|---|---|---|
| `teamId` | string | No | The Team identifier to perform the request on behalf of. |
| `slug` | string | No | The Team slug to perform the request on behalf of. |


## Request body

Required: No

Content-Type: `application/json`

```json
{
  "type": "object",
  "required": [
    "slug",
    "kind",
    "environments"
  ],
  "properties": {
    "slug": {
      "type": "string",
      "description": "A unique (per project) key for the flag, composed of letters, numbers, dashes, and underscores",
      "pattern": "^[a-zA-Z0-9_-]{1,512}$"
    },
    "kind": {
      "description": "The kind of flag",
      "enum": [
        "boolean",
        "string",
        "number",
        "json"
      ]
    },
    "variants": {
      "type": "array",
      "description": "The variants of the flag",
      "items": {
        "type": "object",
        "required": [
          "id",
          "value"
        ],
        "properties": {
          "id": {
            "type": "string",
            "description": "The id of the variant"
          },
          "label": {
            "type": "string",
            "description": "A label for the variant"
          },
          "description": {
            "type": "string",
            "description": "A description of the variant"
          },
          "value": {}
        }
      }
    },
    "environments": {
      "type": "object",
      "description": "The configuration for the flag in different environments",
      "additionalProperties": {
        "type": "object",
        "required": [
          "active",
          "pausedOutcome",
          "rules",
          "fallthrough"
        ],
        "properties": {
          "active": {
            "type": "boolean"
          },
          "reuse": {
            "type": "object",
            "description": "Allows linking this environment to another environment so this flag will be evaluated with the other flag's configuration",
            "required": [
              "active",
              "environment"
            ]
          },
          "targets": {
            "type": "object",
            "description": "Allows assigning targets to variants while bypassing the flag's rules"
          },
          "pausedOutcome": {
            "type": "object",
            "required": [
              "type",
              "variantId"
            ]
          },
          "rules": {
            "type": "array"
          },
          "fallthrough": {},
          "revision": {
            "type": "number",
            "description": "The revision of the environment config"
          }
        }
      }
    },
    "seed": {
      "type": "number",
      "description": "A random seed to prevent split points in different flags from having the same targets",
      "minimum": 0,
      "maximum": 100000
    },
    "description": {
      "type": "string",
      "description": "A description of the flag"
    },
    "state": {
      "type": "string",
      "enum": [
        "active",
        "archived"
      ]
    },
    "maintainerIds": {
      "type": "array",
      "description": "The user ids of the maintainers of the flag",
      "items": {
        "type": "string",
        "maxLength": 24
      }
    },
    "permanent": {
      "type": "boolean",
      "description": "Whether this flag is marked as permanent, indicating it should not be removed"
    },
    "tags": {
      "type": "array",
      "description": "Tags for categorizing the flag",
      "items": {
        "type": "string",
        "maxLength": 64
      }
    }
  }
}
```

## Example request

### TypeScript

```typescript
const response = await fetch('https://api.vercel.com/v1/projects/projectIdOrName/feature-flags/flags?teamId=string&slug=string', {
  method: 'PUT',
  headers: {
    'Authorization': 'Bearer YOUR_ACCESS_TOKEN',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "slug": "string",
    "kind": "boolean",
    "variants": [
      {
        "id": "icfg_1234567890",
        "label": "string",
        "description": "string",
        "value": "string"
      }
    ],
    "environments": "value",
    "seed": "123",
    "description": "string",
    "state": "active",
    "maintainerIds": [],
    "permanent": "true",
    "tags": []
  }),
});

const data = await response.json();
console.log(data);
```

### Next.js

```typescript
'use server';

export async function callEndpoint() {
  const response = await fetch('https://api.vercel.com/v1/projects/projectIdOrName/feature-flags/flags?teamId=string&slug=string', {
    method: 'PUT',
    headers: {
      'Authorization': `Bearer ${process.env.VERCEL_ACCESS_TOKEN}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      "slug": "string",
      "kind": "boolean",
      "variants": [
        {
          "id": "icfg_1234567890",
          "label": "string",
          "description": "string",
          "value": "string"
        }
      ],
      "environments": "value",
      "seed": "123",
      "description": "string",
      "state": "active",
      "maintainerIds": [],
      "permanent": "true",
      "tags": []
    }),
    next: { revalidate: 3600 }
  });

  if (!response.ok) {
    throw new Error('Request failed');
  }

  return response.json();
}
```

### cURL

```bash
curl -X PUT 'https://api.vercel.com/v1/projects/projectIdOrName/feature-flags/flags?teamId=string&slug=string' \
  -H 'Authorization: Bearer YOUR_ACCESS_TOKEN' \
  -H 'Content-Type: application/json' \
  -d "{
    \"slug\": \"string\",
    \"kind\": \"boolean\",
    \"variants\": [
      {
        \"id\": \"icfg_1234567890\",
        \"label\": \"string\",
        \"description\": \"string\",
        \"value\": \"string\"
      }
    ],
    \"environments\": \"value\",
    \"seed\": \"123\",
    \"description\": \"string\",
    \"state\": \"active\",
    \"maintainerIds\": [],
    \"permanent\": \"true\",
    \"tags\": []
  }"
```

## Example response

```json
{
  "description": "string",
  "variants": [
    "value"
  ],
  "id": "icfg_1234567890",
  "environments": "value",
  "kind": "boolean",
  "revision": "123",
  "seed": "123",
  "state": "active",
  "maintainerIds": [],
  "permanent": "false",
  "tags": [],
  "slug": "string",
  "createdAt": "123",
  "updatedAt": "123",
  "updatedBy": "string",
  "createdBy": "string",
  "ownerId": "example_id",
  "projectId": "example_id",
  "typeName": "flag"
}
```

## Responses

### 201: No description

Content-Type: `application/json`

```json
{
  "type": "object",
  "required": [
    "createdAt",
    "createdBy",
    "environments",
    "id",
    "kind",
    "ownerId",
    "projectId",
    "revision",
    "seed",
    "slug",
    "state",
    "typeName",
    "updatedAt",
    "variants"
  ],
  "properties": {
    "description": {
      "type": "string"
    },
    "variants": {
      "type": "array",
      "items": {
        "type": "object"
      }
    },
    "id": {
      "type": "string"
    },
    "environments": {
      "type": "object",
      "additionalProperties": {
        "type": "object",
        "required": [
          "active",
          "fallthrough",
          "pausedOutcome",
          "rules"
        ],
        "properties": {
          "reuse": {
            "type": "object",
            "required": [
              "active",
              "environment"
            ]
          },
          "targets": {
            "type": "object"
          },
          "revision": {
            "type": "number"
          },
          "pausedOutcome": {
            "type": "object",
            "required": [
              "type",
              "variantId"
            ]
          },
          "fallthrough": {},
          "active": {
            "type": "boolean",
            "enum": [
              false,
              true
            ]
          },
          "rules": {
            "type": "array"
          }
        }
      }
    },
    "kind": {
      "type": "string",
      "enum": [
        "boolean",
        "json",
        "number",
        "string"
      ]
    },
    "revision": {
      "type": "number"
    },
    "seed": {
      "type": "number"
    },
    "state": {
      "type": "string",
      "enum": [
        "active",
        "archived"
      ]
    },
    "maintainerIds": {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "permanent": {
      "type": "boolean",
      "enum": [
        false,
        true
      ]
    },
    "tags": {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "slug": {
      "type": "string"
    },
    "createdAt": {
      "type": "number"
    },
    "updatedAt": {
      "type": "number"
    },
    "updatedBy": {
      "type": "string"
    },
    "createdBy": {
      "type": "string"
    },
    "ownerId": {
      "type": "string"
    },
    "projectId": {
      "type": "string"
    },
    "typeName": {
      "type": "string",
      "enum": [
        "flag"
      ]
    }
  }
}
```

### 400: One of the provided values in the request body is invalid.
One of the provided values in the request query is invalid.

### 401: The request is not authorized.

### 402: The account is missing a payment so payment method must be updated

### 403: You do not have permission to access this resource.

### 404: No description

### 409: No description

### 410: No description

---

## Related

- [feature-flags endpoints](/docs/rest-api#feature-flags)

- [REST API overview](/docs/rest-api)

- [OpenAPI spec](https://openapi.vercel.sh/) (machine-readable, all endpoints)

---

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