You can integrate API to the workspace with the following steps -
Step 1: Click on 'Connect to an API' on your workspace -
Step 2: Select an integration from a list of integrations -
Say if you selected Hunter.io as an integration.
Step 3: Click on 'Integrate' button on top right -
Step 4: Bring your API key and add relevant information needed for the integration and click 'Save'.
Step 5: You can see the added API in your configured APIs -
Step 6: Done! You've now added the integration to the workspace. Now you can use it when selecting a column type 'API' or 'Push Button' to the workspace.
Check out this article here on how to use API at the column level or even configure a push button at the column.
Note: Slack integration has a different flow at the table level, cannot be used at the column level. Rest all APIs can be used at the column level.