Hivex keeps a live index of 540,000+ short .si names nobody has claimed, 67,000+ of them already confirmed free with the registry. .si reads as super intelligence. Filter by what you are building, check any name live in one click, or use the free API. Free, no sign-up: filters for length, style and use case (AI agents, assistants, dev tools, fintech), shareable shortlists, and a JSON API with no key.