Testing stolen credentials—even if you didn't steal them yourself—is illegal in most jurisdictions under the Computer Fraud and Abuse Act (CFAA) in the U.S. and similar laws globally. Law enforcement actively monitors large-scale credential stuffing operations.

: Beyond just checking if a login works, these tools often scrape additional data such as the account type (Free vs. Premium), country, and expiration date.

If you are determined to explore these waters despite the warnings, at least learn to identify the obvious scams:

Specifically configured to manage CSRF tokens and session headers to avoid IP bans. Detailed Logging: