Username Blacklist
Username blacklists and blocklists for platforms. Learn which usernames should be blocked and how to enforce restrictions programmatically.
What is a Username Blacklist?
A username blacklist (also called a blocklist) is a collection of usernames that platforms prevent from registration. These include system terms, brand names, government identifiers, security-related terms, and support terms. Blacklists protect platform integrity and prevent user confusion.
Rather than maintaining hardcoded lists, use the username.dev API to check usernames programmatically with up-to-date category coverage.
Common Blacklist Categories
System & Infrastructure
Rules →Technical usernames like admin, root, and api that platforms block to prevent conflicts with core functionality and administrative access.
Brand Names & Trademarks
Rules →Trademarked company names and brand identifiers that platforms protect to prevent impersonation and trademark infringement.
Government & Official Entities
Rules →Government agencies, law enforcement, regulatory bodies, and official institutional identifiers.
Security & Authentication
Rules →Security-related terms like login, password, and verify that could be exploited for phishing and credential theft.
Support & Customer Service
Rules →Help desk, customer service, and support-related terms that users associate with official assistance channels.
Why Hardcoded Blacklists Break
Maintaining a hardcoded blacklist creates problems:
- Lists become outdated as new brands and terms emerge
- Category coverage is incomplete
- No metadata about why a username is blocked
- Manual updates are error-prone
The username.dev API provides programmatic checks with category metadata and automatic updates.
Test This with Your Own Username
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Programmatic Enforcement
Check usernames against blacklists programmatically: