Username Rules for System & Infrastructure
Technical usernames like admin, root, and api that platforms block to prevent conflicts with core functionality and administrative access.
Why These Usernames Are Reserved
System usernames are the most commonly exploited handles in phishing attacks. When someone messages you from @admin, you assume authority. Platforms block these to prevent impersonation of staff, conflicts with subdomain routing (like api.example.com), and bugs caused by programming keywords like null and undefined. Every platform from Twitter to Discord reserves these from day one.
Common Examples
API Enforcement
Check usernames in this category programmatically:
Related Pages
Username Rules
Browse all rule categories
Reserved Usernames
Overview of reserved usernames
Username Rules for Security & Authentication
Security-related terms like login, password, and verify that could be exploited for phishing and credential theft.
Username Rules for Support & Customer Service
Help desk, customer service, and support-related terms that users associate with official assistance channels.