The script for the format constitutes colon, space, and some combination of smart algorithms. After the proxy is detected, you can now sort them according to your desire and wish. The speed for proxy detection varies with the site used for the purpose and on your status whether you are a free user or a premium user. Generally for all the proxy checkers, the duration for checking by a single server is 30 seconds. It is also advisable to be a premium user to enjoy all the features, to become so, you are to give a certain amount in the beginning.