Overview
Custom fields extend contacts with typed data (text, number, date, dropdown backed by custom values, etc.). They appear in the contact editor, filters, merge tags, and workflow conditions.
Configuration
Open #/custom-fields to define fields. Use Custom values when you need shared option sets for dropdowns.
Workflows
The Custom field changed trigger starts workflows when a monitored field updates. The Update field action writes values from automation.
REST access is provided via CustomFieldsController.