For those interested in the technology, it is much safer to study —such as Multi-Factor Authentication (MFA), CAPTCHAs, and device fingerprinting—which are the methods companies like Netflix use to defeat these very tools.
Downloading and executing files like poses significant security risks to the person using them:
Because these tools exist in unregulated "grey-hat" or "black-hat" forums, they are frequently bundled with trojans, keyloggers, or "redline" stealers. The person trying to "check" accounts may end up having their own personal data stolen.
Using these tools to access accounts that do not belong to you is a violation of the Computer Fraud and Abuse Act (CFAA) in the US and similar cybercrime laws globally.