Web push notifications allow you to send notifications to website users in their browsers. The technology can reach a maximum of 80% of users because it works on popular browsers across Windows and Android. No iOS yet though.
Open rates are 0.5% - 15%, so this performs similarly well to email, but not as well as native push messages or SMS.
Expect click-through rates between 15% and 30%. As with native push, you'll do better to keep you messages personalised, relevant and timely.
Some sites are reporting up to 25% increase in web traffic through well targetted push notifications. 80% of people receiving and engaging with web push notifications are mobile users.