Possessing or sharing unauthorized credentials is illegal under international data protection laws like GDPR or the Computer Fraud and Abuse Act (CFAA).
Use reputable services like Have I Been Pwned to see if your email address has appeared in a known data breach. Download 194K MAIL ACCESS VALID COMBOLIST MIX txt
Use a password manager to generate and store strong, unique passwords for every account. This ensures that a leak on one site does not compromise others. This ensures that a leak on one site
These lists are compiled from multiple historical data breaches, phishing campaigns, or "infostealer" malware logs. Combolists and ULP Files on the Dark Web
MFA is the most effective defense against combolist attacks, as it requires a second verification step even if the attacker has your correct password. Combolists and ULP Files on the Dark Web - Group-IB
If you are concerned your own data is on such a list, do not search for the list itself. Instead: