If you are a developer looking to test a new bot or server feature, you can:
Creating automated accounts is a direct violation of Discord’s Terms of Service . Using or distributing these tools can result in permanent bans for your primary account and your IP address.
Discord requires all users to be at least 13 years old , and automated systems often bypass the safety features intended to protect younger users. Legitimate Alternatives
Some users use them to quickly create "alternate" accounts to bypass server bans or to stay anonymous.