Abstract: A system and method for providing a screen sharing service through an extension tool are disclosed. The method can be comprising: receiving a request for a screen sharing-related extension tool for installation in a web browser from a first user terminal; providing the screen sharing-related extension tool in response to the request; receiving a screen sharing request according to execution of the screen sharing-related extension tool installed in the first user terminal; transmitting a screen sharing request notification message to a second user terminal corresponding to the screen sharing request; receiving a screen sharing-enabled status notification message from the second user terminal; and transmitting the screen sharing-enabled status notification message to the first user terminal, thereby establishing a connection for screen sharing between the first user terminal and the second user terminal.