User authentication using a browser cookie shared between a browser and an application

A method comprising:

• receiving, by a computer system associated with a service provider and from a first merchant application of a user device, (i) a data file generated for a second merchant application of the user device and (ii) transaction data associated with a first transaction between a user of the user device and a first merchant, wherein the first merchant application is associated with the first merchant, wherein each of the first merchant application and the second merchant application is a non-browser application, wherein the data file indicates a previous authentication associated with the user for a second transaction conducted between the user and a second merchant associated with the second merchant application via the user device and stored in a memory portion of the user device associated with the second merchant application;
• authenticating, by the computer system, the user for using a user account of the user with the service provider for the first transaction based on the data file and the transaction data;
• and
• transmitting, by the computer system, information to the first merchant application, wherein the information enables the first merchant application to process the first transaction using the user account.

A non-transitory machine-readable medium having stored thereon machine-readable instructions executable to cause a machine associated with a service provider to perform operations comprising:

• receiving, from a first merchant application of a user device, (i) authentication data associated with a user of the user device and generated for a second merchant application of the user device, and (ii) transaction data associated with a transaction between the user of the user device and a first merchant associated with the first merchant application, the authentication data generated based on previously authenticating the user for a previous transaction between the user and a second merchant associated with the second merchant application and stored in a memory portion of the user device associated with the second merchant application, and each of the first merchant application and the second merchant application being a non-browser application;
• authenticating the user for using a user account of the user with the service provider for the transaction based on the authentication data and the transaction data;
• and
• transmitting information to the first merchant application, wherein the information enables the first merchant application to process the transaction using the user account.