And what are positions of your clients? If everything ok, so why do you push the panic button?))
I also have semalt.semalt.com in my statistics. I thought it’s spam. FYI I don’t think it’s bad. Googlebot is monitoring websites either.
Crawler is a tech bot that are often called “web spider”. Googlebot is also crawler but it is responsible for other tasks: webpages indexing for search engine results.
Semalt service performs SEO analysis and further optimization of websites. One of unique features of Semalt is creating lists of competitors for our clients. We have to monitor the web for relevant pages. This doesn’t affect website of our clients, because Semalt bots only harvest information. But if a website owner doesn’t want to appear in the competitors list, they can use the Semalt Crawler removal tool. For more instructions click here.