# Fill in API Keys
source: https://developer.mastercard.com/donations/tutorial/how-to-install-and-configure-insomnia-tool/fill-api-keys/index.md

## Fill In API Keys {#fill-in-api-keys}

* Sign in to Mastercard Developers. Create a Project with the APIs you would like to use (for example, Locations) or use an existing Project. ![Create Project](https://static.developer.mastercard.com/content/donations/uploads/insomnia-mcdev-project.png)
* Fill in the details of your **Consumer Key, Path to Keystore (.p12), Key Alias, and Keystore Password** . See the illustration below for the Sandbox environment. You can do the same for Production environment if you have an approved Production key. ![Create Project](https://static.developer.mastercard.com/content/donations/uploads/insomnia-sandbox-environment.png)
* Click **Done** to close the Manage Environments dialog. Now, you are ready to call the APIs that are authorized by the keys you fill in.