These instructions apply for non Google Cloud Platform (GCP) APIs. If you're building a GCP application, see using API keys for GCP.

If your client application does not use OAuth 2.0, then it must include an API key when it calls an API that's enabled within a Google Cloud Platform project. The application passes this key into all API requests as a key=API_key parameter.

To create your application's API key:

1. Go to the API Console.
2. From the projects list, select a project or create a new one.
3. If the APIs & services page isn't already open, open the left side menu and select APIs & services.
4. On the left, choose Credentials.
5. Click Create credentials and then select API key.

Note: In addition to reading the instructions on this page, be sure to read Best practices for securely using API keys.