Shopify

Step 1: Log in to your Shopify admin panel and go to “Apps” menu. Click on “Manage Apps”

Step 2: At the end of your “Installed Applications” page, you will see a button that reads “Develop apps for your store”. Click on the button there.

Step 3: If this is the first time you are visiting this page, click on “Allow custom app development” button. And then click "Create an app".

Step 4: Introduce App name as (e.g. “Hello world”) and save. Your application will be created and you will have access to all the required information. Go to API Credentials to see everything.

Further info:

https://www.putler.com/support/faq/how-to-get-shopify-api-key-and-password/