How to Mark a Field as Required in Amazing Fields

Trello does not have a native way to enforce required fields on cards. Amazing Fields provides a visual approach using conditional styling: you can configure a field to display in red when it is empty, making it immediately obvious to users that the field needs to be filled in.

How it works

You create a styling rule that changes the field’s background color based on whether it has a value. When the field is empty, it shows red. Once a value is entered, the color clears. This approach works for any field type.

When you create a new card, you will immediately see a red field that should be completed.

Setting up a required field

1. Open Amazing Fields Settings by clicking the Amazing Fields icon in the top-right corner of the board.
2. Select the field you want to mark as required.
3. Go to the "Background Color" section of the field settings.
4. Add a new rule: set the background color to red when the field value is empty.
5. Save the field. Cards with this field empty will now show a red background.

Front-of-card visibility

The required field indicator also appears on the front of the Trello card, so team members can see at a glance which cards are missing important information without opening the card.

Applying this to other field types

The same technique works for any field type where an invalid or missing value should be flagged. For example, you could mark a number field as invalid if its value is less than 10, or flag a date field if it is in the past. Adjust the styling rule condition to match your validation logic.