Best Practices

create_url and Prefill Options

Always link the user with the create_url (available in a Zap template object) in order to create the Zap. Optionally, you can add additional parameters to the create_url so that the user’s Zap is prefilled with the provided custom values.

Note: You will need to know the fields that your app requires per step. You can find the fields as definied in your Zapier integration.

Each parameter is in a flattened dictionary/object syntax. For example an object: {a: {b: 2}} would be flattened to: a__b=2. This allows you to provide countless prefills onbehalf of the user.


Prefill Trello’s board ID (field: board) in the second step of the Zap template:

Here’s what it would look like in the editor:

If you’d like to provide a label for the value (e.g. a Board’s name) you can do so by passing an additional parameter: