.si vs .ai: Is .si the Next .ai?

The short answer. .ai is the established choice, and you pay for it: a two-year minimum, $120 to $200 up front and few good names left. .si is the extension for the term that is replacing AI: the industry talks about superintelligence, and since Executive Order 14434 of 29 September 2026 the US federal government officially says Super Intelligence (SI). .si costs about $12 to $20 a year and is open to everyone, but the obvious words went fast in the September rush. For most new projects, check both and keep the one you can get.

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The two at a glance#

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Cost#

.ai is expensive by design. Every registration and renewal covers at least two years, and per-year prices sit far above most extensions. In Axath's registrar price table, a year of .ai runs from about $60 at Cloudflare to about $100 at GoDaddy, so the first payment is often $120 to $200 before anything is built. Over five years the same name can cost several hundred dollars, more at an expensive registrar; .com vs .io vs .ai works through the numbers.

.si is priced like an ordinary country extension and registers for a single year. The registry charges registrars a flat €10 a year, with no premium tier, and kept that fee unchanged through the rush. Retail prices sit just above it: Dynadot asks $12.05 for the first year and $13.51 to renew, Porkbun $20.42 and $17.53. Five years of .si costs less than the first payment on a .ai, and holding several candidates while you decide is cheap.

Prices move, so compare them live: the .si and .ai pages list the current prices at each registrar.

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Availability#

.ai has been the default for AI products since 2023, so short, clean words are mostly registered or sold as premium names.

.si was wide open until September 2026, and it is still far less crowded than .ai, but the rush changed the picture quickly. 46,066 .si names were registered in September, and by 1 October the extension held 241,459 names. Investors went for exactly the names an AI company would want: more than 44,000 .si names, about a fifth of the extension, mirror an existing .ai name letter for letter, and around half of the early registrations at one registrar were listed for resale at once.

So expect the most obvious AI words to be taken or listed for sale, and expect plenty of good second choices to be free. The fastest way to see the difference is to check the same list in both: paste twenty candidate names into the checker, select .si and .ai, and compare what is free.

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Signal and trust#

.ai tells a reader "AI company" instantly. That signal is the main reason people pay for it.

.si is where that signal may be moving. AI labs now describe their goal as superintelligence (Safe Superintelligence, Meta Superintelligence Labs, Recursive Superintelligence). On 22 September 2026 President Trump told the UN General Assembly that US documents would use "the much more accurate term super, as opposed to artificial", and on 29 September Executive Order 14434 made "Super Intelligence" and "SI" the official terms across the federal executive branch. Within 25 hours of the speech, daily .si registrations had overtaken .ai. If "SI" catches on the way "AI" did, .si follows the path .ai took in 2023.

It is still early. The order changes federal vocabulary, not the law or everyday speech, and only around 3% of new .si names at Hostinger relate to AI at all. Outside the AI crowd many visitors will still read .si as Slovenia's extension.

Either way, keep the .com in mind. People type .com by habit, so if your .si or .ai name has a .com twin that someone else owns, some of your traffic and email will go to them.

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Risk#

Both are country code extensions, so both depend on a country's registry policy.

• .ai earns Anguilla a large share of its government revenue, about EC$230 million (around US$85 million) in 2025 by local reports, which gives the island every reason to keep it stable and open. The registry's move onto Identity Digital's systems in 2025 put it on the same infrastructure as many large extensions.
• .si is run by Slovenia's academic network under published rules that are open to everyone, and it answered the rush without changing its fee or rules. It has never had this much outside demand, though, and the money involved is small for now: the extra September revenue is estimated at around €300,000, so Slovenia has far less riding on .si than Anguilla has on .ai.

The bigger .si risk today is the market, not the registry. Much of the extension is now held by investors betting on a word. If "SI" fades, so do aftermarket prices; if it sticks, the good names get expensive fast.

Neither extension carries the political question that hangs over .io. Read Is .io Safe? for that story.

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Which to choose#

• Pick .ai if the AI signal is central to your brand, the name you want is free, and the two-year price does not matter to you.
• Pick .si if you want a short, brandable name in an AI-adjacent space without .ai prices, or the .ai you wanted is taken.
• Hold both for a name you are serious about. One redirects to the other, and nobody can squat the twin.
• Skip the aftermarket premium on a .si until you have checked a dozen alternatives. At €10 a year from the registry, a free name beats a listed one.

New to .si? Start with What Is a .si Domain?.