The best alternatives to Wallert are Visualping, Followistic, and TV Premiere Alert. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of Wallert?
General Collaboration— One inbox for all your work discussions
Visualping is a simple service for monitoring websites for changes. You'll receive an email notification when it detects any change in the content of the page. You can either choose to monitor the whole website or just an area of a website.
I built a free way for developers, product and customer support to receive a daily alert of new reviews of their app (or competitors). Totally free - hope you like it!