In January 2021, we released the Submit Form API endpoint to give Marketo Engage integrators the ability to submit to Marketo Forms through a supported and authenticated REST endpoint. Thanks to customer feedback we were able to identify a lack of parity for critical functionality such as correct handling of duplicate records and support for Program Member Custom Fields. These issues blocked some integrators from successfully onboarding onto the Submit Form API endpoint.
In our August release, we have enhanced the Submit Form endpoint to handle duplicate records the same way as Marketo forms. When there are duplicate records that match an email address submitted to the form, the endpoint will update the record with the most recent Last Modified Date.
In our October 22, 2021 release, we plan to release support for Program Member Custom Fields for the Submit Form REST API endpoint. We understand that integrators will need time to update and test these new changes before they can fully onboard onto the Submit Form endpoint. To allow additional time for migration, we are delaying blocking programmatic POSTs to the /save2 endpoint to our January 21, 2022 release. This will be the final extension.
Programmatic submissions to our form endpoints remain unsupported despite this delay. Please work to update integrations submitting via this method to one that is supported: Marketo Engage forms on Landing Pages or using the embed code, our Forms2.js API, or the Submit Form API endpoint.