Embodiments are provided that include the use of a cancellable command application programming interface (API) framework that provides cooperative multitasking for synchronous and asynchronous operations based in part on a command timing sequence and a cancellable command API definition. A method of an embodiment enables a user or programmer to use a cancellable command API definition as part of implementing a responsive application interface using a command timing sequence to control execution of active tasks. A cancellable command API framework of an embodiment includes a command block including a command function, a task engine to monitor the command function, and a timer component to control execution of asynchronous and synchronous tasks based in part on first and second control timing intervals associated with a command timing sequence. Other embodiments are also disclosed.