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“Reason” and “Source” Attributes for a Lead’s Activity Simply Say “Web Service API”

Last update: Thu Feb 05 2026 00:00:00 GMT+0000 (Coordinated Universal Time)

Description description

Issue Description
When a lead is created through an API call, the Reason and Source attributes say “Web Service API” with no further detail.

Resolution resolution

Issue Resolution
As described in the doc here, https://docs.marketo.com/display/DOCS/Understanding+System+Managed+Fields, “Source” and “Reason” fields are managed by Marketo:

  1. Web Service API for Original Source Type means Person was discovered by a web service API.
  2. For Registration Source Type, it states that Person was created via SOAP/REST API

When a lead is created via API, no additional “Source” or “Reason” is provided to Marketo.

A possible workaround is to create a custom field and populate it as needed through the API.

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