The best part about SumoMe is that it is literally free to use, no hidden charges and no onetime payments. It works on all sites, whether it is WordPress or HTML, SumoME will not complain about working on these sites. It offers a variety of popups like the boxes which appear when the user clicks on something, a timer which persuades people to subscribe or a before you leave popup. Overall, it is indeed an incredible tool to grow your email list.
Unbounce also lets you create sticky bars for your site. These bright forms draw attention to the offers and help to get more conversions without paying for more traffic. The editor allows you to add pop-up windows (which are called overlays here) on exit, on arrival, after a delay, on a scroll, or on click. There are plenty of pop-up templates to choose from, and you may also customize them. This feature is not available with Instapage.