First, We told you that this article that discussing ICQ Invisible Checker is only web base Invisible Checker. We not sure that the site that we discuss here is safe or work properly in the future. But, it always worthy to try it.
ICQ Invisible Checker Detector
Invisible is a kind of status that usually used by the ICQ user to make it online but not been seen by other ICQ Users (including friends). This almost likes Invisible in Yahoo Messenger. If in Yahoo Messenger has Yahoo Invisible Checker, in ICQ also has ICQ Invisible Checker or Invisible Detector
Below one of the ICQ Invisible Checker that you can visit and try. By visiting this site, we not responsible of any kind happen in the future. You take your own responsibility.
Copy paste the link above and open it in your web browser (Firefox recommended). Type the desired ICQ ID / User that you want to check whether they online, offline, or invisible. This site also provides Yahoo Invis Checker.
ICQ Status Checker | Offline Online Invisible Detector Software
Alternatively, You can also use ICQ Status Checker to check whether some one Invisible or not in ICQ. You may need to login in ICQ or just login by using second anonymous number.
Temporarily there is no protection against ICQ Status Checker, that means that every invisible contact can be detected, independently which client he is using. Besides, the XStatus (from status manager), the registration date and the login and idle time will be displayed additionally (in case the user is wheter offline nor invisible).