Methods and systems for providing merchant in-context checkout are described. A user is authenticated based on credentials received from a first application running on a computing device. An authentication code is provided to the first application. A signed verifier and the authentication code is then received from a second application running on the computing device. The authentication code and the signed verifier received from the second application are then validated, and a device token is provided to the second application upon validation. The device token is exchangeable by the second application for an access token that is usable for making payment calls from the second application.