ExploreSync is an intrusive application that may be installed on your Mac without your knowledge. Typically, this happens via fake downloads, misleading offers, software bundles, and other shady tricks. Users who do not pay close attention to the files they download may end up unknowingly introducing ExploreSync to their computer. This app is not dangerous, but it may bring undesired changes to Web browsers. For example, Potentially Unwanted Programs (PUPs) like this one may set a random website as your browser's new tab page or search aggregator. Because of this, your searches may deliver subpar results, or you might end up seeing unwanted ads.
Unfortunately, PUPs like ExploreSync tend to be quite problematic for Mac users since these users tend to ignore the importance of using reliable security tools. Keeping your Mac secured sufficiently should be more than enough to keep intrusive apps like ExploreSync away from your computer.
Even if ExploreSync has already gotten to your hard drive, you should not be too worried. This issue can be fixed by using a suitable Mac security scanner to help you remove intrusive PUPs fully.