A massive openbulletwordlist (e.g., 50GB) is unusable. You need to balance size with quality. Here is how professionals optimize:

SecLists is the gold standard for penetration testers. Located on GitHub, it contains password lists, usernames, and specific web payloads. While not strictly "OpenBullet formatted" (it usually lacks the email separator), you can easily append a domain to create one using command line tools.

For bespoke testing, generating a wordlist is smarter than downloading random files from the internet (which may contain malware).

# Simple combolist generator
usernames = ["admin", "user", "test"]
passwords = ["123456", "password", "admin123"]
with open("custom_openbulletwordlist.txt", "w") as f:
    for user in usernames:
        for pwd in passwords:
            f.write(f"user:pwd\n")

Troy Hunt's HIBP aggregates billions of real-world breached accounts. While you cannot download the raw passwords directly from HIBP, you can use tools like PwnedPasswords API to check if a password exists. For wordlists, researchers look for publicly dumped breaches (e.g., Collection #1, Antipublic, Exploit.in).