.si is the country-code domain of Slovenia. Since September 2026 it has a second life: "SI" is now the shorthand for superintelligence, and .si reads as an address for SI companies the way .ai became the address for AI companies. This guide covers the facts you need before you register or buy one, each linked to its source.
.si at a glance
| Question | Answer |
|---|---|
| Who runs it | Register.si, operated by ARNES, Slovenia's academic and research network |
| Who can register | Any person or company, anywhere, first come first served |
| Length | 2 to 63 characters, including Slovene and other accented letters |
| Registration term | 1 to 5 years, renewable |
| Price | EUR 10 a year wholesale; about $12 to $24 a year at retail registrars |
| Changing your mind | 16 days to return a new name, if it was never activated |
| When a name expires | Up to 30 days in quarantine (pending delete), then free for anyone |
| Disputes | An arbitration procedure run by the registry, usually 2 to 3 months |
| Size | 317,243 domains on 6 October 2026, after 46,066 new ones in September |
Sources: the registry's home page, general terms and tariff.
Why .si suddenly matters
On 22 September 2026 the US president told the United Nations that the government would call artificial intelligence "super intelligence", and on 29 September he signed an executive order applying the change across federal agencies (Domain Name Wire, Netcraft). Registrations exploded. The registry recorded 3,515 new .si names in August and 46,066 in September (register.si), and on 6 October it showed 19,357 new names in a single day.
Domain investors had been buying for months before that. The first clear company purchase was recursive.si, bought for $20,000 by Recursive, an AI lab that describes its mission as superintelligence. Most other sales so far have been between investors. Our .si sales tracker lists every reported sale with prices.
Who can register a .si domain
Anyone. The registry's terms define a holder as any natural or legal person, with no residency requirement and no need for a Slovenian company (general terms, clause 2.7). Names are assigned first come, first served, through any of the registry's 94 accredited registrars.
A handful of names are reserved: 112.si and 113.si (Slovenia's emergency numbers), si.si and rs.si (held for the Republic of Slovenia), and three technical names blocked for security reasons (reserved names).
What a .si domain costs
The registry charges registrars EUR 10 a year before VAT, a price unchanged since January 2023, and it does not control what registrars charge you (tariff). On 6 October 2026, a first year cost $12.00 at Dynadot (renewal $13.46), $11.99 at Hostinger (renewal $16.99) and $20.38 on sale at Porkbun. For comparison, .ai costs $160 wholesale for a minimum of two years.
A name someone already owns is a different matter: its price is whatever the owner asks. Reported .si sales range from under $100 for two-word compounds to $34,000 for ai.si. The sales tracker shows what different kinds of names sell for.
The rules that trip people up
- Characters. Letters a to z, digits, hyphens and accented letters (internationalised names such as roža.si). No hyphen at the start or end, and the two-character minimum counts the accented form, so č.si is not allowed (general terms, clause 4).
- Returning a new name. You can cancel within 16 days of registration, but only if the name was never activated, meaning no name servers were submitted (registration and return).
- Term limits at registrars. The registry allows 1 to 5 years, but some registrars sell fewer; Hostinger, for example, caps .si at 3 years.
- Expiry. A name that is not renewed goes into quarantine, shown as pending delete, and drops out of DNS. Quarantine lasts no longer than 30 days; the holder can still renew during it, and after it the name is deleted and anyone can register it (general terms, clauses 5.4.2 to 5.4.3).
- Privacy. For individuals, the public registry record shows only an email address. Paid WHOIS privacy products are generally not offered for .si.
- Your email address. Keep it working: the registry can delete a name if it cannot reach the holder by email.
Transfers and changing owners
A purchase usually needs one or both of these moves, and the registry charges nothing for either (tariff):
- Changing the holder (registrant). The registrar makes the change after both the current and the new holder confirm, and the registry then emails both parties. The registration period stays as it was.
- Changing the registrar. The holder picks a password, turns it into a SHA-256 digest with the calculator on the registry's transfers page (the password never leaves your browser), gives the digest to the current registrar, and gives the plain password to the new one. A transfer does not add or remove time from the registration.
For valuable names, ask your registrar for a Registry Lock. Once it is set, nobody can change the domain except to renew it, and unlocking needs a written request that the registry verifies by phone during office hours (registry lock). Step-by-step buying advice is in our guide on how to buy a domain that's taken.
Disputes over a .si name
If someone registered a .si name that infringes your rights, you can file a complaint in the registry's alternative dispute resolution (ADR) procedure. Cases are decided by independent arbiters and enforced by the registry (ADR guidelines):
- You must show a right valid in Slovenia (such as a trademark or company name), that the holder has no legitimate interest, and bad faith in registration or use (general terms, clause 18.2.1).
- Complaints are filed only through the online form, and proceedings are in Slovenian, although English evidence is usually accepted.
- The domain is blocked from transfer or deletion as soon as a complete complaint is filed. The holder has 21 days to respond, the arbiter decides within 14 days of appointment, and a typical case takes 2 to 3 months.
- The fee for one to five domains is EUR 700 including VAT for a single arbiter (fees).
Is a .si domain good for SEO?
Google says country-code domains "provide a strong signal" that a site targets that country, and .si is not on its list of generic country codes treated like .com, unlike .ai, .io and .co (Google Search Central). So a .si site starts with a lean toward Slovenia in Google's results. Searches in other countries can still be won, but it takes more work than with a .com. Many companies use a .si name as a brand or a redirect alongside their main domain.
How to get a good .si name
- Check if it is free. Search any registrar, or look the name up in the registry's RDAP service. A "not found" answer usually means the name is free, though reserved names also return nothing.
- If it is taken, buy it. Many premium .si names are listed with a public price. Our guide on buying a taken domain safely covers escrow and the transfer.
- If it is about to expire, wait. A name in quarantine is deleted within 30 days and then free; a backorder or a quick registration can catch it.
Be careful with look-alikes: a .si name is one keystroke away from its .ai twin, and security researchers have flagged that as a typo-squatting risk (Netcraft).
FAQ
Can I register a .si domain if I am not in Slovenia?
Yes. The registry lets any natural or legal person hold a .si domain, with no residency requirement and no need for a Slovenian company. You register through any of its accredited registrars, and names are assigned first come, first served.
How much does a .si domain cost per year?
The registry charges registrars EUR 10 a year wholesale. At retail, a first year cost between about $12 and $24 in October 2026 depending on the registrar, and renewals are often a little higher than the first year. Names that are already taken sell for whatever their owner asks.
What does .si stand for?
Officially, .si stands for Slovenia, from Slovenija, the country's name in Slovenian. Since September 2026 it is also read as SI, short for superintelligence, which is why AI companies and domain investors started using it the way they once adopted .ai.
What happens when a .si domain expires?
It goes into quarantine, shown as pending delete, for up to 30 days. During that time the old holder can still renew it, but nobody can buy or transfer it. After quarantine the registry deletes it and anyone can register it again.