A good .si name must first satisfy Register.si’s technical rules, then work for real people. The registry controls characters, length, hyphens and restrictions; your audience decides whether the result is easy to read, say, type and remember.
A .si name has two tests
A good .si name must pass two different tests. First, it must satisfy Register.si’s technical rules for characters, length and hyphen placement. Then it has to work for people: can they read it, say it, type it and remember it? The second test is practical naming advice, not a registry requirement.
.si is Slovenia’s country-code top-level domain, or ccTLD. IANA identifies the Academic and Research Network of Slovenia, ARNES, as its ccTLD manager, while Register.si’s terms identify ARNES as the .si Registry. The letters “si” may suggest different branding ideas, but they do not change the registry’s rules or official meaning.
Characters, length and hyphens
Register.si’s allowed-character table includes the English and Slovene alphabets, Arabic numerals from 0 to 9, the hyphen and internationalised characters from its Latin-1 Supplement, Latin Extended-A and Latin Extended-B lists. Slovenian letters such as č, š and ž are included. The table is a live registry reference observed on October 6, 2026, not a timeless guarantee; check it again before purchasing.
The technical length rule has an IDN detail. A .si name must contain at least two characters and no more than 63. For an internationalised domain name, the minimum applies to the displayed IDN. Register.si gives č.si as an example that fails the minimum even though its ACE form, xn--bea.si, is longer. The 63-character maximum is measured against the ACE string.
A name cannot begin or end with a hyphen. It also cannot contain consecutive hyphens in the third and fourth positions, unless those hyphens form part of the ACE string of an allowed IDN. An example such as bright-lab.si is illustrative only: it has not been availability-checked or reviewed for trademark conflicts.
IDNs: technically valid, practically specific
Internationalised domain names can preserve a spelling that matters to a founder, organisation or local audience. For example, čebelar.si is illustrative only, not an availability result. Register.si permits the relevant character, but technical permission does not answer whether the name is convenient in every setting.
An accented form may be the clearest choice for an audience that routinely uses Slovenian characters. An ASCII alternative may be easier to dictate, type on an unfamiliar keyboard or share with someone who expects basic Latin characters. That is communication analysis, not a claim about conversion, search ranking or adoption. The practical choice depends on the audience, software and channels in which the name will travel.
If both forms matter, a founder can consider an ASCII companion name, but the two names must be checked separately. Their availability, registration status and legal position are not established merely because one is an IDN version of the other.
Valid syntax is not a clean bill of health
The reserved-name list observed on October 6, 2026 includes 112.si for the common emergency number, 113.si for police, rs.si and si.si for the Republic of Slovenia, plus three forbidden Xerox vulnerability names: xeroxdiscoverysupernode1.si, xeroxdiscoverysupernode2.si and xeroxdiscoverysupernode3.si. This is a live list, not a permanent guarantee that no other restriction can apply.
The General Terms require an application to be made in good faith and for lawful purposes, without encroaching on third-party rights. A domain name must not breach law, public order or morals. Register.si may refuse registration or delete a domain when holder obligations are breached. Passing the character and length tests is therefore not trademark clearance or legal approval.
Applications are submitted through registrars. Register.si says the automated first-come, first-served process applies to complete applications accepted by the Registry server; incomplete applications do not enter the queue. Registration also depends on the stated conditions and payment received from the registrar. Quarantine, blocked and locked statuses are lifecycle or post-registration states, not extra character rules.
What RDAP can—and cannot—tell you
Register.si’s RDAP service separates registry information from a successful registrar registration process. A 404 means the entered domain was not found, usually because it is not registered, but Register.si explicitly warns that this does not always mean the name can be registered. A 200 means the domain is registered and/or cannot be registered at that time.
A 400 indicates an invalid request, such as prohibited characters or the wrong TLD. A 429 means access is temporarily restricted because too many requests were made. Register.si also supports HEAD requests for checking whether a domain is already registered without returning further data. Anonymous users do not receive holder or technical-contact information.
Use RDAP as one step in a workflow: draft several names, remove unsupported punctuation, count the label, check hyphen placement, compare IDN and ASCII forms, review the live reserved-name list and then confirm the result through an appropriate registrar. Names such as river-kite.si and studioorbit.si are illustrative only and have not been availability-checked.
The usability test
Once a candidate passes the registry rules, say it aloud. Can another person distinguish every letter? Can you type it from memory? Does the spelling need repeated explanation? Look at it in lowercase beside the .si ending. These tests are editorial preferences, not technical requirements.
A short, pronounceable name is not automatically better, and an internal hyphen is not automatically a problem. The useful question is whether the name suits the situations in which it will be spoken, typed, printed, emailed or shared. The strongest candidate is the one whose technical validity and human clarity agree.
The core .si naming rules
| Question | Official rule or practical meaning |
|---|---|
| Which characters are allowed? | Latin letters, digits 0–9, the hyphen and the internationalised characters listed by Register.si, including č, š and ž. |
| How long can a name be? | At least 2 and no more than 63 characters. For an IDN, the minimum is assessed against the IDN; the maximum is assessed against its ACE representation. |
| Can it start or end with a hyphen? | No. Consecutive hyphens in the third and fourth positions are also restricted, except when they are part of the ACE string of an allowed IDN. |
| Does valid syntax guarantee registration? | No. A name may already be registered, reserved, restricted by policy or unavailable through the registrar’s registration process. |
A few good questions.
What characters can a .si domain contain?
The Register.si table includes English and Slovene alphabet characters, digits 0–9, the hyphen and listed internationalised Latin characters, including č, š and ž.
How long can a .si name be?
A .si name must contain at least two and no more than 63 characters. For an IDN, the minimum applies to the displayed IDN, while the maximum applies to its ACE representation.
Can a .si domain start or end with a hyphen?
No. Leading and trailing hyphens are prohibited. Consecutive hyphens in positions three and four are also restricted, except in the ACE form of an allowed IDN.
Does a .si RDAP 404 mean I can buy the name?
No. It means the entered domain was not found, usually because it is not registered. Register.si warns that a 404 is not a registration guarantee; reserved names, policy restrictions and the registrar’s registration process remain separate checks.
What makes a .si name usable?
Test whether people can read, pronounce, type and remember it in the situations that matter for your audience. Those qualities are practical naming criteria, not registry requirements.
Sources, not assumptions.
Evidence cutoff: 2026-10-06. Prices, policies and domain status can change.
- Register.si — Allowed characters ↗
- Register.si — General Terms (effective 15 November 2024) ↗
- Register.si — Reserved names ↗
- Register.si — RDAP response meanings ↗
- IANA — .si delegation record ↗
What would change this?
- Changes to allowed characters, IDN length interpretation or reserved names.
- Changes to the registry’s registration and third-party-rights conditions.
Independent information, not legal or investment advice. Domain status and prices can change; confirm registry rules and registrar checkout terms before buying.