What Is a .si Domain? The 2026 Guide for Founders

A .si domain is, formally, the country-code top-level domain for Slovenia. But like .ai before it, the two letters carry a second meaning the market has latched onto: "SI" reads as superintelligence, system intelligence, and simply a short, confident "si". You can see the available names on the .si domains page.

What is the .si extension, technically?

.si is Slovenia's ccTLD, a long-established and professionally run namespace. It was never designed for artificial intelligence, but a clean two-letter extension that happens to spell a meaningful acronym is exactly the kind of accident the aftermarket rewards, just as Anguilla's .ai became the AI namespace.

Why have AI brands started using .si?

Because it is short, it is distinctive, and the obvious "SI" reading does positioning work for a frontier-tech brand. For a research lab or an AI-native product, a two-letter extension that gestures at superintelligence is a sharper signal than a longer, more literal name on a crowded extension. The category that gives .si its meaning, frontier AI and world-models research, is also well funded, which underpins demand.

Is a .si domain right for your brand?

It is a strong fit if you want a short, modern, slightly insider signal and your audience is technical. It is a weaker fit if you need universal familiarity from a non-technical, mass-market audience, where a .com still carries broader trust. The honest test is whether the "SI" signal means more to your buyers than mainstream recognition.

How do you buy a .si domain?

The clean, meaningful .si names are registered and trade on the aftermarket rather than at a registrar. You request the price on the domain page, agree terms, and the transfer is secured through escrow so your funds release only once the name is yours. The full process is on How it works, and the economics of category-defining extensions are covered in why .ai domains are so expensive.

Browse the .si portfolio or read the FAQ for ownership and transfer details.