Some web addresses are too long to be easy to remember and spread, so web address shortening services are born in response to needs. Because of the rise and popularity of microblog, web address simplification tools spring up in large numbers. However, with the "dumping" of some micro-blogs and URL shortening services one after another, many of the addresses of technical articles collected by netizens have become dead chains in a certain sense. What if I can't open these links? In fact, it is only a certain sense of the dead chain, you can use the following five short chain recovery services to find its original address: