Custom fields on customers and subscriptions

Historical retrospective - March–June 2026
This article was written afterwards and describes the feature as it worked during the stated periods.

Custom fields provided a place for integration or workflow data without changing Alunta’s fixed columns. A field has an owner, a stable key, and a data type. Distinguish a customer field from a plan field and a field on a concrete subscription.

Plan, subscription, and customer

A plan field describes the catalogue or agreement that can be sold. A subscription field belongs to one customer’s subscription and can hold an external reference or other agreement-specific value. A customer field belongs to the customer across subscriptions. Create the definition in the relevant settings area and use its stable key when reading or updating the value.

The data type is validated. Do not assume arbitrary JSON is accepted, and a value owned by one object is not automatically moved to another. API responses include field values only where the public reference documents the relevant owner; a field existing in settings does not mean every surface displays it.

Why is a value rejected? Check the key, type, and whether the field belongs to a plan, subscription, or customer.

Does the field appear in webhooks/API? Only where the current public contract includes that owner.

See the plans and pricing guide (Markdown file, AI agent-friendly).