Myproxychecker.com is one of the best proxy checkers online because
- can check the proxies if are dead or alive
- you can check both http and socks proxies
- it will show you the location for each proxy
- tells you if the proxy is anonymous or not
- it will tell you the speed of each proxy
- you can customize on which URL you want to check
- you can pick which proxies you want to export
- is free and fast