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Custom response lets you attach arbitrary JSON metadata to a product and return it in every validate response. Use it to deliver feature flags, entitlement data, or any other configuration your application needs at runtime.

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Requirements

Custom response is a paid plan feature. Enable it for your product in the KeyPort dashboard.

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The custom field

When custom response is enabled and configured, the validate endpoint returns a custom field containing your JSON payload:
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custom
object | null
A merged JSON object containing product-level metadata and any license-level overrides. Returns null if the feature is disabled or the merged object is empty.
{
  "valid": true,
  "custom": {
    "tier": "pro",
    "features": ["exports", "analytics"]
  }
}

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How the payload is built

KeyPort merges two sources to produce the custom value:
  1. Product template — the default metadata defined on your product
  2. License override — optional metadata set on the individual license
When both are present, the license override wins on any conflicting keys. This lets you define a baseline payload at the product level while customizing it per customer.
Use the product template for defaults that apply to all licenses, and use license overrides only for fields that differ per customer.

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When custom is null

The custom field returns null in two cases:
  • The custom response feature is disabled for your product
  • The merged object is empty after combining the product template and license override
Check for null before accessing fields on custom in your application code.