---
updatedAt: 2026-03-16T18:37:11.000Z
agentTools:
  projectIndex: https://docs.split.io/llms.txt
---

# Authentication

Learn how to authenticate your requests to the Split API using API keys, personal access tokens (PATs), or service account tokens (SATs).

Most requests to Split's API are authenticated with an **Admin API key**. Some requests are authenticated with a client-side or server-side **SDK API key**.

The **Admin** key can be finely-tuned to provide access to your Split resources. Creating an API key is simple, as described on the [Create an API Key](https://docs.split.io/reference/create-an-api-key) page under the **API Keys** section.

> 📘 Learn more about API keys
>
> To best familiarize yourself with using API keys in Split, refer to the [API keys](https://developer.harness.io/docs/feature-management-experimentation/management-and-administration/account-settings/api-keys/) guide in our main documentation site for more information.
>
> To learn more about **Admin API Key** roles and scopes, just check out [API keys overview](https://docs.split.io/reference/api-keys-overview)

You can also authenticate with a Harness [personal access token (PAT)](https://developer.harness.io/docs/platform/automation/api/api-quickstart/#create-a-harness-api-key-and-token) or a [Service Account Token (SAT)](https://developer.harness.io/docs/platform/automation/api/add-and-manage-api-keys#create-service-account-api-keys-and-tokens). Both are supported for all non-deprecated Split API endpoints.

## Choose a credential type

* **Admin API keys**: Provide fine-grained access to Split resources. For more information about roles and scopes, see [API keys overview](https://docs.split.io/reference/api-keys-overview).
* **SDK API keys**: Used with client-side or server-side SDKs.
* **Harness PATs**: Issued through the Harness platform, and valid for authenticating against supported Split APIs. Use these in place of Admin API keys if you already manage authentication centrally in Harness.
* **Harness SATs**: Issued to service accounts in Harness, and valid for authenticating against supported Split APIs. Use these for automated integrations or workloads that require long-lived credentials tied to a non-human account.

## Authentication Header

Credentials must be sent in the appropriate HTTP header, depending on the token type. Replace the placeholder with your own key or token. Use one header per request; do not include both `Authorization` and `x-api-key` at the same time.

Substitute `ADMIN_API_KEY` with your **Admin API key**.

```text
Authorization: "Bearer ADMIN_API_KEY"
```

Substitute `SDK_API_KEY` with your client-side or server-side **SDK API key**.

```text
Authorization: "Bearer SDK_API_KEY"
```

Substitute `HARNESS_PAT` with your **Harness Personal Access Token (PAT)**.

```
x-api-key: "HARNESS_PAT"
```

For more information on creating and managing PATs, see the [Harness documentation](https://developer.harness.io/docs/platform/automation/api/api-quickstart/#create-a-harness-api-key-and-token).

Substitute `HARNESS_SAT` with your **Harness Service Account Token (SAT)**.

```
x-api-key: "HARNESS_SAT"
```

For more information on creating and managing SATs, see the [Harness documentation](https://developer.harness.io/docs/platform/automation/api/add-and-manage-api-keys#create-service-account-api-keys-and-tokens).