sessionTimeout is a jQuery plugin to display a dialog with the option to either "log out now" or "stay connected", after a set amount of idle time.
iziToast is an elegant, responsive, flexible and lightweight notification plugin with no dependencies. All modern browsers are supported (Tested in Chrome, Firefox, Opera, Safari, IE10+ and Edge)
humane.js is a simple, modern, framework-independent, well-tested, unobtrusive, notification system. Utilizes CSS transitions when available, falls back to JS animation when not. Includes mobile support.
ssi-modal is an open source modal window plugin created by using jQuery. It has many options and it's super flexible. Responsive Mobile friendly Customizable Full feature
overhang.js is a jQuery plugin to display sleek, instant notifications, confirmations or prompts inside a given element.