Regex · Username · Free
Username regex.
Matches a username of 3–16 letters, digits, or underscores. Copy the pattern below, see what it matches, then tweak it for your exact case with the free generator.
The pattern
/^[a-zA-Z0-9_]{3,16}$/
✓ Matches
jane_doeuser123AI_builder✗ Doesn't match
abhas spaceway_too_long_username_hereNeed a variation? Generate one
Other common patterns
Parsing and pattern-matching are everywhere in AI systems. MindloomHQ teaches you to build them for real — agents, RAG, pipelines — with projects and certificates.
Explore MindloomHQ →