A .si domain is Slovenia’s country-code top-level domain. Arnes, the Academic and Research Network of Slovenia, runs it through its registry service Register.si, and IANA lists April 1, 1992 as its registration date. Anyone in any country can register a .si domain through an accredited registrar for a term of 1 to 5 years.
The extension is also having an unusual year. For AI companies, .si reads as SuperIntelligence, an informal reading with no official status. Register.si counted 172,227 .si domains at the end of 2025 and 295,465 as of October 5, 2026. The jump followed a public debate about a new name for artificial intelligence that drew attention to .si.
This guide covers the rules, the real costs, how Google reads the extension, and how to buy or transfer a name someone already owns. Every registry figure comes from Register.si, IANA or the .ai registry and carries a date, because the counters change daily.
What is a .si domain?
A .si domain is an internet address under the country-code top-level domain of Slovenia. The IANA root zone record for .si names the Academic and Research Network of Slovenia (Arnes) in Ljubljana as the manager of .si domains and gives April 1, 1992 as the registration date. Register.si, the registry service of Arnes, sets the rules, keeps the database and works only through accredited registrars.
Register.si treats April 1, 1992 as the birthday of the extension. Arnes itself dates from May 7, 1992, so the domain is a few weeks older than the organization that runs it. Since April 4, 2005, registrars have handled all new registrations instead of the registry.
Security features arrived early: Register.si switched on DNSSEC for its authoritative servers on December 1, 2011, and the DS records for .si reached the DNS root on December 24, 2011. DNSSEC lets resolvers check that nobody altered the DNS answers on the way.
Most holders are companies: the registry’s 2025 annual report puts businesses at 66.8% of holders and individuals at 33.2%. The 10 largest registrars hold 77% of all .si domains.
The table below sums up the .si domain, the official Slovenia domain extension, with live counters as of October 5, 2026.
| Item | .si at a glance |
|---|---|
| Country | Slovenia |
| Registry | Register.si, run by Arnes |
| IANA registration date | April 1, 1992 |
| Who can register | Any legal or natural person, no residency or local contact needed |
| Name length | 2–63 characters |
| Allowed characters | a–z, 0–9, hyphen, plus IDN letters such as č, š and ž |
| Registration term | 1–5 years |
| How to register | Through an accredited registrar (93 as of October 5, 2026) |
| Registry fee | €10 per domain, same for all registrars (Register.si, September 24, 2026) |
| DNSSEC | Since December 2011 |
| Disputes | ARDS, the registry’s own tribunal |
| After expiry | Up to 30 days in quarantine, then free to register again |
| Domains registered | 295,465 as of October 5, 2026 |
Who can register a .si domain
Any person or company, in any country, can register a .si domain. The registry’s General Terms define a holder simply as a legal or natural person, with no rule on residency, citizenship or a local contact.
For a foreign founder, that removes the usual ccTLD hurdle. A company in Austin or London follows the same steps as one in Ljubljana and pays whatever its registrar charges.
The registry hands out names on a first come, first served basis. If two registrars ask for the same free name, the request that reaches the registry first wins.
A few names never reach the open market, because the General Terms reserve 113.si for the police, 112.si for civil protection, and si.si and rs.si for the government.
Privacy rules depend on who holds the name: for companies, the public WHOIS shows the holder, the technical contact and the registrar. For individuals, it shows only a contact email address, in line with GDPR.
How to register a .si domain, step by step
You register a .si domain through an accredited registrar, never directly with the registry, and the process has four steps.
- Check availability. Search the name at any registrar. Keep the length and character rules below in mind, since the registry rejects any name that breaks them.
- Choose an accredited registrar. Register.si lists 93 registrars as of October 5, 2026, and says you cannot register directly with the registry. Compare first-year and renewal prices before you pick one.
- Pick a term of 1 to 5 years. The General Terms allow registration or renewal for 1, 2, 3, 4 or 5 years. A longer term protects a brand name against a missed renewal.
- Activate DNS. Point the domain to your name servers. If your registrar asks the registry to delete the domain within 16 days of registration and the domain has not been activated, the registry refunds the fee to the registrar, so ask your registrar whether it passes that refund on. Entering DNS servers counts as activation and closes that window.
That 16-day rule matters more than it looks. If you register the wrong spelling and set up DNS the same afternoon, the option to cancel is gone, and you own the typo for the full term.
Naming rules: length, hyphens and IDN
A .si name must have between 2 and 63 characters. The registry does not accept one-character names such as č.si, so single letters are off the table.
Hyphens can sit inside a name but not at the start or the end. A double hyphen in positions 3 and 4 only works for a valid IDN name, because encoded IDN names use that pattern.
Beyond a–z, 0–9 and the hyphen, Register.si accepts an IDN character table that includes the Slovenian č, š and ž, plus letters from the Latin-1 Supplement and Latin Extended-A sets. For IDN names, the 63-character limit applies to the encoded ACE string, not the visible spelling.
For an international brand, we would avoid IDN names. Typing č on a US or UK keyboard takes extra effort, people drop the accent in emails, and you end up buying the plain version anyway to catch lost visits. For a Slovenian audience the case flips: a name with š or ž can read more naturally, as long as you also hold the plain spelling.
.si domain prices: registration, renewal and aftermarket
The registry fee for .si domains is €10 per domain, the same for every registrar, according to a Register.si announcement on September 24, 2026. Retail prices sit above that fee because each registrar adds its own margin and sets its own renewal policy. In our checks on October 5, 2026, first-year prices ranged from $12.04 at Dynadot to €18 at Netim, while EuroDNS charged €12.99 for the first year and €76.50 for each renewal. Always compare the renewal price, not only the first-year offer.
Here are three registrar retail examples, all checked on October 5, 2026. Netim and EuroDNS list their prices excluding VAT, and registrars change prices often, so check again before you buy.
| Registrar | First year (registration) | Renewal | Transfer | Checked |
|---|---|---|---|---|
| Netim | €18 | €18 per year (listed annual price) | Free | October 5, 2026 |
| Dynadot | $12.04 | $13.51 | $0.00 (listed) | October 5, 2026 |
| EuroDNS | €12.99 | €76.50 | €76.50 | October 5, 2026 |
The EuroDNS row shows the renewal trap. The first year costs €12.99, but each renewal costs €76.50, so five years cost about €319 at the prices we checked on October 5, 2026. At Dynadot’s listed prices on the same date, the same five years cost $66.08.
Aftermarket prices follow different logic: a name that someone already owns sells for whatever buyer and seller agree, and the €10 registry fee plays no part.
On September 30, 2026, N1 reported asking prices of $10 million for build.si and $8 million for seed.si. Those are asking prices, not sales, and the report shows no buyer at those levels. In a September 24, 2026 announcement, which N1 quoted, Register.si said media speculation about million-dollar earnings for Slovenia has no real basis.
For comparison, our own portfolio lists 10 curated .si domains at fixed aftermarket prices as of October 2026. They range from €900 for apsplus.si and kyberit.si to €12,000 for the one-word rapid.si. The three-letter mkr.si costs €4,500, and the four-letter llmo.si costs €2,000. Buyers pay through Escrow.com.
No domain is a guaranteed-return investment. Treat any .si purchase as a branding cost first, and assume you may never resell it for more than you paid.
Does a .si domain hurt SEO outside Slovenia?
A .si domain is a country-code domain that Google reads as a signal that a site targets Slovenia. Google’s guide to multi-regional sites says a ccTLD gives “a strong signal to both users and search engines” that a site targets one country. The same guide lists .ai, .io and .co among the ccTLDs it handles as generic. When we checked on October 5, 2026, .si was not on that list. A business that sells mainly in the US or UK should therefore weigh the signal before building its main site on .si.
That list explains why .ai and .io work for global startups even though they are country codes. Google handles them like generic domains such as .com, so their country of origin does not steer targeting. Google notes that the list may change.
The .ai registry FAQ reported 598,007 .ai domains as of January 2, 2025. IANA lists the Government of Anguilla as the manager of .ai, with a registration date of February 16, 1995.
| Feature | .si | .ai | .com |
|---|---|---|---|
| Type | Country code | Country code | Generic |
| Country | Slovenia | Anguilla | None |
| IANA registration date | April 1, 1992 | February 16, 1995 | Not covered here |
| Google treatment | Country signal for Slovenia | Treated as generic | Generic |
| Registered names | 295,465 (Register.si, October 5, 2026) | 598,007 (nic.ai, January 2, 2025) | Not covered here |
| Best fit | Slovenian brands, short AI brand names | Global AI products | Any global business |
A country signal is one input among many, and content and links still matter. Founders who want a .si name can pick one of three setups:
- Main site on .si, aimed at Slovenia. Here the country signal works in your favor. For other European markets it points to the wrong country, like any foreign ccTLD.
- Main site on a generic domain. The .si name serves as a short brand address that redirects to it.
- Main site on .si for a global audience. You accept the Slovenia signal and invest in strong content and links.
Why .si registrations jumped in 2026
The number of .si domains grew by about 72%, from 172,227 at the end of 2025 to 295,465 as of October 5, 2026, according to Register.si. The registry links the rise to a public debate about a new name for artificial intelligence that put the letters SI in the news.
New registrations reached 46,066 in September 2026, against 2,726 in September 2025. The total passed 200,000 in late September 2026, and registrars added 18,878 .si domains in the 24 hours before the October 5, 2026 snapshot.
Growth before 2026 was steady but slow: the registry counted 118,480 domains at the end of 2015, 140,702 at the end of 2020 and 162,648 at the end of 2024. The year 2025 added 6%, ending at 172,227.
The registry’s monthly growth figures show where the break happened. Register.si counted 6,342 new names in May 2026, 6,938 in June and 3,515 in August, then 46,066 in September. Daily numbers stayed high into October, with 11,331 on September 30 and 13,651 on October 4, 2026.
News coverage points to a specific moment. N1 reported on September 25, 2026 that interest in .si rose sharply after a September 19, 2026 social media post. In it, US President Donald Trump floated “Superior Intelligence (SI)” as an alternative name for artificial intelligence. Register.si’s own September 24, 2026 announcement names the same post and says the debate prompted speculation about its effect on the .si domain.
For AI founders, the appeal of superintelligence domain names is easy to see: in an AI context the two letters read as SuperIntelligence. The domain itself still belongs to Slovenia’s namespace and follows Slovenian registry rules.
Search demand is still modest: Ahrefs Keywords Explorer showed 3,300 monthly searches worldwide for “.si domain” on October 5, 2026, with 700 from the US. The same tool showed 11,000 for “.ai domain”, with 2,300 from the US, and close to zero for “superintelligence domain”.
A registration spike says nothing certain about long-term value. The renewal rate a year from now will be the better test, and the same Register.si counters will show it.
Transferring or buying an existing .si domain
Moving a .si domain to a new registrar and changing its owner are two separate procedures. Buying a name from a seller often needs both, plus a safe way to pay.
Changing registrar
To transfer .si domains to a new registrar, the holder asks the current registrar for a password, also called the EPP code or authinfo code. The new registrar submits the transfer with that password. The password stays valid until its first use or for at most 16 days, and the expiry date of the domain does not change on transfer.
Changing the holder
A change of holder needs both sides to agree. The registrar carries out the change, the term stays the same, and Register.si sends an email to both the old and the new holder. If you buy a name, make sure that email reaches you and check the record at your registrar afterward.
Paying safely with escrow
For a paid sale, an escrow service protects both sides, and Escrow.com’s domain escrow process runs in five steps:
- Buyer and seller agree on the price and terms.
- The buyer pays Escrow.com, which holds the money.
- The seller transfers the domain to the buyer.
- The buyer confirms receipt, and Escrow.com checks the transfer.
- Escrow.com releases the funds to the seller.
Escrow.com says it can withhold payment until it is satisfied that the seller has transferred the domain, for example by checking the registrar’s WHOIS record. For a .si name held by an individual, the public record shows only a contact email. That gives the buyer’s confirmation and the registry’s automatic email to both holders more weight. Our own sales follow this pattern: a fixed price, payment held by Escrow.com, then the EPP code or a holder change at the registrar, buyer confirmation and release of funds.
Checks before you pay
Run three checks before you pay for any .si name.
- Trademarks. Search for registered rights that match the name. A holder can lose a domain in a dispute.
- Disputes. .si disputes go to ARDS, the registry’s own dispute tribunal, not WIPO. A complainant must show three things: a name identical or confusingly similar to a right recognized in Slovenia, no legitimate interest by the holder, and registration or use in bad faith. Cases usually take about 2–3 months and run in Slovenian. The ARDS fee for 1–5 domains was €700 including VAT when we checked on October 5, 2026.
- Expiry. An expired name sits in quarantine for up to 30 days. The holder can still renew it during that time. After that, the registry deletes it and anyone can register it again.
Is a .si domain right for you?
For a business in Slovenia, .si is the obvious choice, and for an AI brand that wants a short, distinctive name it is a reasonable one. It is a weaker fit for a site that must rank across the US or UK from day one.
If you run a business in Slovenia
Register the .si, since the country signal works in your favor, the registry fee is low, and local customers expect it. If your name contains č, š or ž, hold both the IDN spelling and the plain one.
If you are building an AI startup for a global market
As our guide to domains for AI startups explains, a .si name gives you a short brand with an AI reading: SuperIntelligence. Weigh that against the Slovenia signal in Google, described in the SEO section above. Two of the setups listed there apply. Put the product on a generic domain and use the .si as a brand or campaign address, or run the main site on .si and invest in content and links.
If you are buying as an investment
Be careful. Asking prices in the news are not sales, and the registry itself questioned the million-dollar talk. Buy a name you would actually use.
Start by checking the exact name at two or three registrars and comparing the five-year cost rather than the first-year price. Then decide where the main site will live before you set up DNS. If the name you want is taken, browse our premium .si domains for sale or the full list of curated .si domains, each at a fixed price with escrow.
