At the end of the month – anyone using Adobe Sign (EchoSign) will be cut off from the API if they’re using any type of outdated authentication that sends the username and password in the request header – commonly used in the SOAP API.
Recently I have completed an upgrade to the V6 Adobe Sign REST api using PHP, and incorporating Oauth into that.
There are various aspects to this, including with/without user login with Adobe – as I my case, there are no requirements for customer registration, just to send out forms and track their status.
Will be updating this post with a tutorial, however currently developers can check out the GitHub repo here: https://github.com/edmunds22/adobe-sign-php