---
title: API overview
description: "An overview of the three main Unleash APIs: Client API, Frontend API, and Admin API."
displayed_sidebar: documentation
---

import SearchPriority from '@site/src/components/SearchPriority';

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## Unleash APIs

Unleash provides a set of APIs to give you full programmatic control over your feature flags and to connect your applications and services to Unleash. There are three main APIs, each designed for a specific purpose.

| API            | Used by | Primary use case |
|---------------|---------|---|
| **Client API** | Server-side SDKs | Fetch feature flag configurations. |
| **Frontend API** | Client-side SDKs | Fetch enabled feature flags for a specific [Unleash Context](/reference/unleash-context). |
| **Admin API** | [Admin UI](/understanding-unleash/unleash-overview#the-unleash-admin-ui), internal tooling, and third-party [integrations](/reference/integrations) | Access and manage all resources within Unleash, such as context, environments, events, metrics, and users. |

## API authentication and tokens

All Unleash APIs require authentication using an [API token](/reference/api-tokens-and-client-keys). The type of token you use depends on the API you are accessing and your specific use case.

### Token types

Unleash supports four types of API tokens:
- **Client tokens**: Used to connect server-side SDKs, Unleash Edge, and the Unleash Proxy to the Client API. Can be scoped to a specific project and environment.
- **Frontend tokens**: Used to connect client-side SDKs to the Frontend API or Unleash Edge. These tokens are designed to be publicly accessible and have limited permissions. Can be scoped to a specific project and environment.
- **Personal access tokens**: Tied to a specific user account. They are useful for testing, debugging, or providing temporary access to tools and scripts that need to interact with the Admin API.
- **Service account tokens**: The recommended method for providing API access to integrations, automation tools, and other non-human users. Service accounts provide a more secure and manageable way to grant Admin API access.

For an end-to-end Unleash integration, you might need to use multiple token types. For example, when connecting a client-side SDK to Unleash using Unleash Edge, you'll need the following tokens:
- A frontend token for the client-side SDK to securely communicate with Unleash Edge.
- A client token for Unleash Edge to communicate with the main Unleash server.

![Diagram showing the types of tokens needed to connect a client-side SDK with Edge, and Edge with Unleash](/img/token-types-example.png)

Ensure that the client token has access to the same project and environment (or a broader scope) as the frontend token.

### Create an API token

Depending on your permissions, you can create API tokens in the Unleash Admin UI in four ways:

- **Admin settings > Access control > API access**: for client or frontend tokens; requires the Admin root role, or a custom root role with API token permissions.
- **Admin settings > Service accounts > New service account**: for creating a service account and assigning a token.
- **Settings > API access** [inside a project]: for project-specific client or frontend tokens; permitted for project Members or users with a corresponding root role.
- **Profile > View profile settings > Personal API tokens**: for personal access tokens.

## API specification

For a comprehensive and interactive reference of all available endpoints, Unleash provides an OpenAPI specification. This is useful for exploring the APIs, generating client libraries, and for testing.

:::note Availability

**Unleash version**: `5.2+` enabled by default.
**Unleash version**: `4.13+` can be enabled using the `ENABLE_OAS` [environment variable](using-unleash/deploy/configuring-unleash).
:::

You can access the specification from your Unleash instance at the following paths:

- **Interactive Swagger UI**: `/docs/openapi/`
- **Raw JSON specification**: `/docs/openapi.json`

For detailed guides on each API, please refer to the full reference documentation.