Our use case involves having a recipient in DocuSign who is only assigned a text field to provide some information. We are able to populate the field with information via the API, but we were wondering if it were possible to also mark the envelope as 'completed'/'signed' via the API?
We've been able to update the fields using the EnvelopeRecipientTabs : update endpoint, but just wanted to check whether we perhaps missed an endpoint for marking an envelope as completed.
Regarding
[Is it] possible to also mark the envelope as 'completed'/'signed' via the API?
No, sorry. That's in the general category of "Robo-signing" which DocuSign does not support.
Instead, I suggest that the tab be assigned to a recipient who really will sign. Your API application can then update the value of the field. If you don't want the signer to change the value, you can use the locked attribute to make it read-only for the recipient.