In leak communities, cracking is referred by “credential stuffing”, originally, cracking is seen as “reverse engineering”, which is “unlocking” a piece of software.
Most people use either Sentry.MBA, OpenBullet, STORM or SNIPR. SNIPR is a premium program and its development was started by Pragma (which I believe is also the dev for PokeSnipr) back in 2015. It costs about 20 bucks in BTC, the bang that you get with SNIPR is continous development and support alongside being programmed in C, however it’s heavily noticed by security companies, SNIPR was documented by Akamai and anti malware companies, this puts SNIPR’s users at liability. SNIPRis great for people that don’t know how to config themselves.
STORM is a free tool, which was discontinued due to its continous abuse, Open Bullet is known for its community-modified versions and API support (eg: restock hits to a shop automatically). Sentry.MBA is the uncrowned king of 2012-2017, a lot of the versions are modified, it is pretty obsolete now.

A config is a “.ini” made to tell the program what to do, a config includes parameters such as HTTP headers, threads (amount of instances running) and proxy support. Most configs use proxies to circumvent a website’s login limiter/security, some are proxyless, proxyless configs are exponentially slower due to pacing with the target’s IP “traffic limiting” or are made to circumvent other checks, such as refreshing cookies. Configs can capture parameters when given the adequate code to do so, EG: capturing a string on a page to determine if an account is premium or not.A proxy server acts as a gateway between you and the internet. It’s an intermediary server separating end users from the websites they browse. Proxy servers provide varying levels of functionality, security, and privacy depending on your use case, needs, or company policy.
If you’re using a proxy server, internet traffic flows through the proxy server on its way to the address you requested. The request then comes back through that same proxy server (there are exceptions to this rule), and then the proxy server forwards the data received from the website to you.

A proxy (server) acts as a gateway between you and the internet. It’s an intermediary server separating end users from the websites they browse. Proxy servers provide varying levels of functionality, security, and privacy depending on your use case, needs, or company policy.
If you’re using a proxy server, internet traffic flows through the proxy server on its way to the address you requested. The request then comes back through that same proxy server (there are exceptions to this rule), and then the proxy server forwards the data received from the website to you.