Three in four addresses that AI engines cite end in .com, and the other quarter depends on what was asked. In the Machine Relations Index answer ledger, 148,868 of 197,384 cited-URL events (75.4 percent, 95 percent interval 74.4 to 76.4) were on a .com website. .org was 5.1 percent, .ai 4.9, .io 3.6, country codes such as .uk and .au together 3.3 and newer extensions such as .app and .dev 3.0.
The extension tracks the topic of the question more than the engine. On the 42 AI-visibility and GEO questions, .ai was 18.7 percent of citations (16.2 to 20.7), and 993 of the 1,350 runs that cited anything (73.6 percent) cited at least one .ai website. On the 42 consumer-products questions, .ai was 0.1 percent. Consumer-health questions drew .gov and .edu at 3.6 and 2.3 percent, education questions drew .edu at 5.7, and sales and CRM questions drew .io at 10.9.
This page counts which extensions cited websites use. It does not say that an extension earns a citation: the Index holds no count of how the web's websites are spread across extensions, so a .com share of 75 percent may be the share of .com on the web.
What was counted #
- Population. Successful runs in the Index's buying-question panel, 2026-07-06 to 2026-11-07, five engines (ChatGPT, Claude, Gemini, Google AI Mode and Perplexity) through their APIs, runs that name a brand in the prompt excluded. This is the same 197,384 cited-URL events, 23,183 runs, 1,008 questions and 29,282 root domains as the URL slug study, the site-sections study and the year-in-the-URL study; the counts reproduce exactly from the ledger export of 2026-11-11 08:10 UTC. Google AI Overviews are left out, and so are the consumer ChatGPT and Claude apps.
- Unit. One cited URL in one answer run, counted once however often the run repeated it. The same address cited in two runs counts twice. Perplexity returns 105,295 of the 197,384 events (53 percent), so the overall shares lean toward Perplexity; the engine table below shows each engine alone.
- Extension. The last label of the cited website's root domain as the ledger records it (the registered domain, public-suffix aware, so
bbc.co.ukis.ukandgithub.iois.io). Subdomains do not change it. - Groups. .com, .org, .net, .gov and .edu are counted alone. .ai, .io and .co are counted alone because they are two-letter country codes that companies use as brand extensions. "Other repurposed" holds .to, .sh, .me, .so, .cc, .gl, .vc, .ws, .tv, .ly, .gg, .fm, .ac, .ag and .im. "Country codes" is every other two-letter extension (.uk, .au, .us, .ca, .in, .eu, .de, .jp and the rest). "New extensions" is every other extension longer than two letters (.app, .dev, .tech, .network, .security, .health and the rest). "Other older generics" holds .info, .biz, .mil and .int.
- Intervals. 95 percent intervals resample the 1,008 questions with replacement, keeping every cited address of a question together (2,000 draws, fixed seed). Vertical intervals resample the 42 questions of that vertical (1,000 draws).
The overall mix #
| Extension | Events | Share | 95% interval | Websites | Share of websites |
|---|---|---|---|---|---|
| .com | 148,868 | 75.4% | 74.4 to 76.4 | 20,413 | 69.7% |
| .org | 10,047 | 5.1% | 4.6 to 5.5 | 1,171 | 4.0% |
| .ai | 9,677 | 4.9% | 4.4 to 5.5 | 1,543 | 5.3% |
| .io | 7,177 | 3.6% | 3.3 to 4.0 | 1,083 | 3.7% |
| Country codes | 6,569 | 3.3% | 3.1 to 3.6 | 2,343 | 8.0% |
| New extensions | 5,868 | 3.0% | 2.7 to 3.2 | 1,250 | 4.3% |
| .net | 2,471 | 1.3% | 1.1 to 1.4 | 536 | 1.8% |
| .co | 2,188 | 1.1% | 1.0 to 1.2 | 422 | 1.4% |
| .gov | 1,700 | 0.9% | 0.7 to 1.0 | 115 | 0.4% |
| .edu | 1,483 | 0.8% | 0.6 to 1.0 | 190 | 0.6% |
| Other repurposed | 1,130 | 0.6% | 0.5 to 0.7 | 158 | 0.5% |
| Other older generics | 206 | 0.1% | 58 | 0.2% | |
| All | 197,384 | 29,282 |
.ai out-cites .io by 1.3 percentage points (interval 0.8 to 1.8), a gap that does not reach zero. Counted by website, .ai is 5.3 percent of cited websites and .io 3.7, and a .ai website is cited 6.3 times on average against 6.7 for the whole set, so .ai is spread over many sites, not a few big ones: the ten most-cited .ai websites hold 14.9 percent of .ai events, and 37.7 percent of .ai websites were cited exactly once, against 40.2 percent of .com ones.
Two extensions are concentrated. One website, nih.gov, is 800 of the 1,700 .gov events (47.1 percent), and arxiv.org is 1,433 of the 10,047 .org events (14.3 percent). A website on a country code was cited 2.8 times on average and a .gov website 14.8, which is why country codes are 8.0 percent of cited websites and 3.3 percent of citations.
At the run level, 27.8 percent of runs (6,442 of 23,183) cited only .com websites. The rest cited at least one other extension: .org in 25.0 percent of runs, .ai in 22.8, .io in 21.6, a new extension in 19.5, a country code in 19.4, .gov in 4.3 and .edu in 4.1.
The question's topic sets the extension #
Share of cited-URL events by vertical. The Index panel has 24 verticals of 42 questions each; these are eleven that show the range.
| Vertical | Events | .com | .org | .ai | .io | Country codes | .gov | .edu |
|---|---|---|---|---|---|---|---|---|
| AI visibility and GEO | 12,965 | 64.1% | 1.0% | 18.7% | 6.1% | 2.3% | 0.1% | 0.4% |
| AI security and privacy | 11,728 | 54.3% | 11.5% | 15.8% | 6.0% | 2.3% | 0.7% | 0.7% |
| AI infrastructure | 9,978 | 53.9% | 6.1% | 13.9% | 8.6% | 2.4% | 0.2% | 0.9% |
| Sales, GTM and CRM | 3,459 | 69.0% | 0.8% | 12.9% | 10.9% | 1.0% | 0.0% | 0.0% |
| Martech and advertising | 4,236 | 78.2% | 1.2% | 5.3% | 8.5% | 2.1% | 0.0% | 0.0% |
| Fintech | 8,512 | 71.9% | 2.7% | 3.7% | 8.1% | 1.4% | 0.1% | 0.1% |
| Healthcare services | 8,379 | 75.3% | 6.5% | 5.3% | 1.8% | 1.7% | 3.6% | 0.4% |
| Consumer health | 12,832 | 72.4% | 11.5% | 0.2% | 0.2% | 6.1% | 3.6% | 2.3% |
| Education and training | 9,405 | 75.1% | 7.6% | 1.7% | 2.4% | 1.7% | 0.1% | 5.7% |
| Consumer products | 12,423 | 86.4% | 4.5% | 0.1% | 0.2% | 5.6% | 0.8% | 0.4% |
| Consumer finance | 11,850 | 89.2% | 4.4% | 0.2% | 0.6% | 1.2% | 0.9% | 0.4% |
The four AI-and-software verticals at the top hold 38,130 events, and .ai is 16.0 percent of them against 2.2 percent of the other 20 verticals' 159,254 events. They hold 63.2 percent of all .ai events. Intervals on the .ai share: AI visibility and GEO 16.2 to 20.7, AI security 12.7 to 19.5, AI infrastructure 12.1 to 15.8, sales and CRM 10.0 to 16.1, consumer products 0.0 to 0.3 and consumer health 0.1 to 0.3. The consumer-health .gov share is 2.1 to 5.1 percent and the .org share 8.3 to 15.6; the education .edu share is 2.8 to 9.3.
The obvious reading is the right one: the questions in those verticals are about AI products, and AI companies often register .ai websites. The .ai share is a trace of what is being asked about, not a sign that engines prefer an extension.
AI-visibility and GEO questions #
This is the vertical this site is about, so it is worth a closer look. The 2,427 .ai events come from 427 different websites, and the ten largest (otterly.ai, llmpulse.ai, dageno.ai, siftly.ai, averi.ai, trysight.ai, topify.ai, optimizegeo.ai and two more) hold 30.1 percent of them. Take those ten out and .ai is still 13.9 percent of the remaining events. By engine, .ai is 22.1 percent of ChatGPT's AI-visibility citations, 20.8 of Claude's, 20.3 of Gemini's, 17.1 of Perplexity's and 12.2 of Google AI Mode's. .io is 786 events from 155 websites, led by frase.io (89 events).
The engines differ a little #
Share of each engine's cited-URL events.
| Engine | Events | .com | .org | .ai | .io | Country codes | New extensions |
|---|---|---|---|---|---|---|---|
| ChatGPT | 35,357 | 71.5% | 5.0% | 4.9% | 3.8% | 5.8% | 4.2% |
| Claude | 33,192 | 75.7% | 5.2% | 6.0% | 4.3% | 1.9% | 2.9% |
| Gemini | 17,416 | 74.7% | 4.2% | 6.9% | 3.5% | 3.3% | 3.4% |
| Google AI Mode | 6,124 | 78.9% | 3.2% | 5.7% | 3.9% | 3.1% | 2.2% |
| Perplexity | 105,295 | 76.6% | 5.4% | 4.2% | 3.4% | 3.0% | 2.6% |
ChatGPT cites country-code websites three times as often as Claude (5.8 against 1.9 percent) and .com the least (71.5 percent). Gemini cites .ai the most (6.9 percent) and Perplexity the least (4.2). Perplexity cites .gov and .edu the most, at 1.1 and 0.9 percent; Google AI Mode cites .edu the least, at 0.3. The engines do not answer the same questions (Perplexity cites on all 1,008, Google AI Mode on 138), so a difference between two engines can come from the questions each answered; the vertical mix is not held fixed here.
The shape of the question moves .org, .gov and .edu #
Share of cited-URL events by question shape (168 questions each).
| Question shape | Events | .com | .org | .ai | .io | Country codes | .gov | .edu |
|---|---|---|---|---|---|---|---|---|
| Best X | 38,847 | 75.9% | 4.2% | 5.8% | 3.3% | 3.5% | 0.5% | 0.6% |
| How to choose | 31,480 | 73.1% | 5.2% | 6.0% | 4.0% | 3.4% | 1.3% | 0.7% |
| Is X worth it | 30,652 | 74.8% | 4.2% | 5.9% | 4.3% | 2.6% | 1.1% | 0.8% |
| Problem first | 26,258 | 70.9% | 8.0% | 4.1% | 3.5% | 5.0% | 1.4% | 1.2% |
| Top list | 39,901 | 77.6% | 4.1% | 4.3% | 3.8% | 3.2% | 0.4% | 0.2% |
| X vs Y | 30,246 | 78.8% | 5.8% | 3.1% | 2.9% | 2.5% | 0.7% | 1.3% |
A buyer who describes a situation and names no product draws the least .com (70.9 percent) and the most .org (8.0 percent), country codes (5.0) and .gov plus .edu (2.6). A buyer who asks for a top list or a head-to-head comparison draws the most .com (77.6 and 78.8 percent). Top lists draw the fewest .gov and .edu together, 0.6 percent.
What this changes #
- Do not read the extension as a lever. The data shows which extensions get cited on which questions. It does not show that moving a site from .com to .ai, or the reverse, changes anything. A company on a .com website is on the extension three in four cited addresses use, and an AI company on a .ai website is on the extension one in five AI-visibility citations use.
- Judge the competitor set by topic. If a report says "engines cite .ai websites", ask for the vertical. In AI-visibility, AI security and AI infrastructure answers it is 14 to 19 percent. In consumer answers it is nearly zero.
- Institutional extensions matter on problem and health questions. .gov, .edu and .org together were about 17 percent of consumer-health citations, 13 percent of education ones and 10.5 percent of problem-first ones. A page that needs to be cited there competes with sources that no vendor can buy: government, university and nonprofit pages.
- Check a metric that sums by extension. A share of citations by extension depends on the question set and on Perplexity's weight in the total. 75.4 percent .com is a property of this panel, not of the web.
What this page does not show #
- Any effect of an extension on citation. The ledger has no matched pairs of otherwise similar pages on different extensions, and no count of the web's websites by extension to compare against.
- Any ranking of engines. The engines answered different questions, and the vertical mix is not held fixed.
- Websites, brands or products. An extension is the end of a root domain; a brand can own several, and the ledger records the one engines cited.
- Language or country of the reader. Country codes are what the root domain ends in, not who the page is for. Many .com websites are not American and many country-code websites are global.
- The consumer apps and Google AI Overviews. Not included.
Related parties #
Machine Relations Research is owned by Bramwell, Inc., which also owns AuthorityTech. Both sites are in the data and are counted like any other: machinerelations.ai, a .ai website, is cited in 7 of the 9,677 .ai events, and authoritytech.io, a .io website, in 57 of the 7,177 .io events (51 of them on AI-visibility questions). Removing both would move no overall share by more than 0.03 percentage points; on AI-visibility questions it would take .io from 6.1 to 5.7 percent and leave .ai at 18.7.
Method note #
Source: the Index answer ledger's citation-events table, daily export of 2026-11-11 08:10 UTC, read with DuckDB and joined to the run table. Filters: the buying-question panel (mri_v2), runs not flagged as brand-prompted, successful runs, run dates 2026-07-06 to 2026-11-07, engines ChatGPT, Claude, Gemini, Google AI Mode and Perplexity: 197,384 distinct (run, cited URL) events, 23,183 runs, 1,008 questions, 29,282 root domains, reproduced exactly as in the sibling studies before any new count. The extension is the last dot-separated label of the recorded root domain. Percentages are shares of events unless a table says websites or runs. Intervals are percentile intervals from question-level resampling with Python's random module, seed 20261111 for the overall table and seed 11 for the vertical intervals, 2,000 and 1,000 draws. The .ai against .io difference uses seed 7. Groupings are stated in "What was counted".
Frequently asked questions #
Which domain extensions do AI engines cite most? #
.com, by a wide margin. In the Machine Relations Index ledger, 75.4 percent of 197,384 cited addresses were on a .com website, then .org (5.1 percent), .ai (4.9), .io (3.6), country codes together (3.3) and newer extensions such as .app and .dev together (3.0).
Do AI engines cite .ai websites? #
Yes, and the share depends on the question. .ai was 4.9 percent of all citations, 18.7 percent on AI-visibility and GEO questions and 0.1 percent on consumer-product questions. About 74 percent of the AI-visibility runs that cited anything cited at least one .ai website.
Does a .com domain help a page get cited by AI? #
The data cannot say. Three in four cited addresses are .com, but the Index has no count of how many websites on the web are .com, so the share may only reflect that .com is the most common extension. No test here compares otherwise similar pages on different extensions.
Do AI engines cite .gov and .edu websites? #
A little, and mostly on health and education questions. .gov was 0.9 percent of citations and .edu 0.8 percent. Consumer-health questions drew .gov at 3.6 and .edu at 2.3 percent, and education questions drew .edu at 5.7 percent. One website, nih.gov, was 47 percent of all .gov citations.
Does the engine change which extensions it cites? #
Somewhat. ChatGPT cited country-code websites in 5.8 percent of its citations and Claude in 1.9. Gemini cited .ai the most (6.9 percent) and Perplexity the least (4.2). The engines answered different sets of questions, so these differences are not clean engine rankings.
Is .io or .ai cited more? #
.ai. It was 4.9 percent of citations against 3.6 for .io, a gap of 1.3 percentage points (interval 0.8 to 1.8). .io was ahead of .ai in 13 of the panel's 24 verticals, by the widest margins in fintech (8.1 against 3.7 percent), igaming and betting (7.6 against 2.2) and martech and advertising (8.5 against 5.3). In the four AI-and-software verticals at the top of the vertical table, .ai led.