Is it possible to do OAuth2 authentication like facebook/ google login, which only requires users to enter their username & password, without providing their client_id & client_secret?
The steps displayed here require the user to provide his client_id & client_secret for authentication. http://developers.marketo.com/documentation/rest/authentication/
Currently the Marketo platform does not offer OAuth2 authentication similar to Facebook login or Google login.
Here is how the Marketo authentication process currently works for the REST API. A Marketo custom service must first be created. Once a custom service is created, you will have access to a client id and client secret. You will use the client id and client secret to generate an access token via the REST API authentication endpoint. You will then use this access token to make subsequent requests to the REST API, such as to query lead data.