> ## Documentation Index
> Fetch the complete documentation index at: https://developers.kit.com/llms.txt
> Use this file to discover all available pages before exploring further.

# API V3 Authentication

## API key

All API calls require the `api_key` parameter. You can find your API Key in the Kit [developer settings page](https://app.kit.com/account_settings/developer_settings) under the `V3 Key` section.

<img width="800" alt="API V3 key" src="https://mintcdn.com/kit-314e57c1/dSCrspkEWxNDV3Va/images/api/v3-api-key.png?fit=max&auto=format&n=dSCrspkEWxNDV3Va&q=85&s=175f3626b495d9e015ae27023ac4975e" data-path="images/api/v3-api-key.png" />

## API secret key

Some API calls require the `api_secret` parameter. All calls that require `api_key` also work with `api_secret`, there's no need to use both. This key grants access to sensitive data and actions on your subscribers. You should treat it as your password and shouldn't use it in any client-side code (usually that means JavaScript).

This can also be found in the Kit [developer settings page](https://app.kit.com/account_settings/developer_settings) under the `V3 Key` section.

<img width="800" alt="API V3 key" src="https://mintcdn.com/kit-314e57c1/dSCrspkEWxNDV3Va/images/api/v3-api-key.png?fit=max&auto=format&n=dSCrspkEWxNDV3Va&q=85&s=175f3626b495d9e015ae27023ac4975e" data-path="images/api/v3-api-key.png" />

## Integration Key

We no longer support the creation of new integration keys for V3 of the API. If you would like to build a new integration with Kit, please refer to our documentation for [building apps for the Kit App Store](/kit-app-store/overview). If you encounter any issues with your integration key for a pre-existing integration, please reach out to the [Kit support team](https://kit.com/support), who will be able to assist you.