Choosing between .com, .ai, .io and .si.
The short answer
Do not hunt for a single dictionary word: they are nearly all taken, on every ending but .dev. Pick a brand-style name instead, a word with an ending such as flow or hub, and the endings look very different: 90% of those names were still free as .si, 70% as .ai and 14% as .com when we checked each one with its registry. A .si costs from $10.95 a year. Take the .com when your name is free there; for an AI product, .si gives you the most choice at a fraction of the price of .ai.
Where the names are.
How many of 480 brand-style names were free on each ending on 12 October 2026, from Hivex's availability study, and the lowest price we have verified for each.
| Ending | Names still free | First year from | Renewal from |
|---|---|---|---|
| .siMost names leftSlovenia’s code, open to anyone; read as “super intelligence”. | 90% | $10.95Atom | $11.54Dynadot |
| .comThe original commercial ending. | 14% | $11.08Porkbun | $11.08Porkbun |
| .aiAnguilla’s code, the ending AI products expect. | 70% | $82.70Porkbun | $82.70Porkbun |
| .ioThe British Indian Ocean Territory’s code, popular with developers. | 68% | $28.12Porkbun | $51.80Porkbun |
| .coColombia’s code, read as “company”. | 69% | $15.76Porkbun | $31.20Porkbun |
| .appGoogle Registry’s ending for apps; HTTPS only. | 74% | $8.75Porkbun | $14.93Porkbun |
| .devGoogle Registry’s ending for developers; HTTPS only. | 82% | $8.75Porkbun | $12.87Porkbun |
.si prices from Hivex's .si price comparison (read 10 October); the others from Porkbun's public list (read 26 October). Prices change; your registrar's checkout is the final word.
What to know about each.
.si: the most names left, for about the price of a .com.
.si is Slovenia's country code, run by Register.si at ARNES since 1992[1], and anyone in the world can register it[2]. Since September 2026 people read it as “super intelligence”, which suits an AI product, and it still has room: 90% of the brand-style names we checked were free, against 14% on .com. It costs from $10.95 a year at Atom. .si domains, explained.
Will a .si hold my site back on Google outside Slovenia?
Google lists most country codes, .si among them, as a hint about which country a site is for, and treats a few, such as .ai, .io and .co, as generic[3]. In practice links and content decide rankings: a study of 4,538 domains found no link between the ending and rank in the US once those were accounted for[4]. Products found worldwide run on such endings, bit.ly (Libya) and jit.si (Slovenia) among them. Write in English, earn links from the countries you sell to, and the ending stops mattering.
.com: the default, if your name is free.
People assume .com, so it is the easiest name to say out loud. Supply is the catch: 14% of the brand-style names and 0 of the 1,000 most common words were free on 12 October 2026. A good .com is usually bought from its owner, not registered. See names for sale.
.ai: the expected ending, at a price.
.ai is Anguilla's country code, treated as generic by Google[3], and the ending AI buyers expect. It costs about 8 times as much as a .si (from $82.70 a year), often sold in two-year terms[5], and 70% of the brand-style names were free.
.io: popular with developers, with a question mark.
.io stands for the British Indian Ocean Territory and Google treats it as generic[3]. In October 2024 the UK and Mauritius announced an agreement on sovereignty over the Chagos Archipelago, the islands that territory covers[6]. What that means for .io has not been decided: IANA still lists the same manager, with no change to the record since January 2023[7]. If you choose .io for a long-lived brand, register a second ending too.
.co, .app and .dev: the other generic choices.
.co is Colombia's code, treated as generic by Google[3], and people sometimes type .com by habit. .app and .dev are run by Google Registry and sit on the browsers' HTTPS preload list, so a site there only works over HTTPS[8][9]: fine for anything modern, and a small security plus. .dev also has the most plain words left: 224 of the 1,000 most common English words were free there on 12 October 2026.
How to decide.
- 01Skip single dictionary words: they are nearly all taken. A word with a short ending, a blend of two words or a made-up name is where the free names are.
- 02Write down three to five names you like and check each on every ending at once: a name free on several endings is worth more than one free on one.
- 03If the .com is free and the price is fair, take it. If it is taken, check whether it is for sale before you settle for another ending.
- 04Match the ending to who will type it: .si or .ai for an AI product, .dev or .io for developers, .co or .app for a general product.
- 05Compare the renewal price, not only the first year: renewals are what you pay for as long as you keep the name.
- 06Search the trademark registers before you print anything: a free domain is not permission to use a name.
Sources
- [1]Wikipedia, .si, updated 1 Oct 2026
- [2]Register.si (ARNES), General terms and conditions for registration under .si, 15 Nov 2024
- [3]Google Search Central, Managing multi-regional and multilingual sites, updated 10 Dec 2025, read 12 Oct 2026
- [4]Search Engine Journal (Kevin Indig), What 4,538 domains tell us about ccTLDs ranking in the US, 16 Jul 2024
- [5]TechCrunch, Slovenia's .si domain sees a surge in registrations after Trump's 'super intelligence' order, 2 Oct 2026
- [6]UK Government, Joint statement between the UK and Mauritius, 3 Oct 2024
- [7]IANA, Delegation record for .io, last updated 18 Jan 2023, read 12 Oct 2026
- [8]Google Registry, .app, read 11 Oct 2026
- [9]Google Registry, .dev, read 12 Oct 2026
By Hivex. Updated 12 October 2026. Prices change; the free shares are from 12 October 2026.