The Open Index by Webtec
The state of AI search and SEO, in numbers you can cite.
Benchmarks from 19 published studies, explained in plain English, compared across industries, and linked to every source. Built by Webtec Research for business owners, agencies and journalists.
58%
lower click-through for the top result when an AI Overview appears
Ahrefs, 2025 to 2026
Written byKris GjorgjioskiKeyword research and industry benchmarks, Webtec Research
Checked byHristijan NajcheskiHead of SEO and AEO (technical and AI SEO), data verification
Updated October 15, 2026 · Edition 1Refreshed quarterly · next January 2027
Built from research on
Google
OpenAI
Perplexity
Gemini
Anthropic
Cloudflare
Semrush
ABOUT THE OPEN INDEX
What it is, who it is for, and why we publish it.
The Open Index is a reference library of benchmarks on AI search and SEO, compiled from published research and refreshed every quarter.
A benchmark library
Nineteen published studies on AI Overviews, clicks, AI referral traffic, citations, crawlers and technical foundations, brought into one place, explained in plain English and compared across industries. Every figure carries its publisher, date, sample size and a link to the original.
People who need numbers they can defend
Business owners weighing where to invest. Marketers and agencies who need a figure to cite in a proposal. Journalists and analysts comparing the major studies. You do not need to be a specialist to follow it.
Better decisions, in the open
Most of what is said about AI search rests on one or two studies, often from a vendor with something to sell. We show where studies agree, where they disagree and why, and where evidence is thin, so you can decide with the full picture.
NOT A BLOG POST WITH NUMBERS IN IT
- Sources firstEach figure is traced to a named study, with date and sample.
- Graded evidenceIndependent research is separated from vendor research.
- Disagreements shownWhen studies conflict we explain why instead of picking one.
- Interpretation labelledOur reading is kept apart from the published findings.
- Checked twiceWritten by Kris, verified by Hristijan before it goes live.
- Re-checked quarterlyCorrections are logged in public.
REFRESHED QUARTERLY
Edition 1 · October 2026
New editions land in January, April, July and October. Next: January 2027.
- Oct 2026Edition 1Published
- Jan 2027Edition 2Next
- Apr 2027Edition 3Planned
- Jul 2027Edition 4Planned
THE TEN FINDINGS
What the evidence says about AI search, in one page.
Each finding gives the number, what it means and where it comes from. Brackets match the source list at the bottom.
Finding 01
58%
lower click-through for the top result when an AI Overview appears
In Ahrefs’ re-run of the same 300,000-keyword test, the top result’s CTR on AI Overview keywords fell from 0.073 to 0.016 between December 2023 and December 2025. The first measurement, in March 2025, found 34.5%, so the estimated loss grew a lot in nine months.[1],[2]
See the dataFinding 02
8% vs 15%
of visits clicked a result with and without an AI summary
Pew tracked 900 US adults. With an AI summary they clicked a regular result in 8% of visits, against 15% without one, and only 1% clicked a link inside the summary.[3] Separately, 58.5% of US Google searches ended without a click in 2024.[4]
See the dataFinding 03
25% · 18% · 16%
of searches show an AI Overview, depending on who measures
Conductor counted 25.11% of 21.9M US searches in autumn 2025;[5] Pew counted 18% of its panel’s searches in March 2025;[3] Semrush counted 15.69% of 10M+ keywords in November.[6] Different keyword sets and dates explain the spread.
See the dataFinding 04
48.75% vs 4.48%
Health Care against Real Estate for AI Overview prevalence
Industry decides exposure. Health Care searches triggered an AI Overview about eleven times as often as Real Estate searches in Conductor’s data.[5]
See the dataFinding 05
1.08%
of website visits come from AI assistants on average
Small, but uneven: Information Technology sees 2.80% and Communication Services 0.25%.[5] Growth is steep from a low base: Adobe measured AI referrals to US retail up 1,300% year on year over the 2024 holidays.[18]
See the dataFinding 06
87.4%
of AI referral traffic comes from ChatGPT
One engine sends almost all of it.[5] That fits the demand side: 34% of US adults had used ChatGPT by spring 2025, and 58% of adults under 30.[7]
See the dataChatGPT 87.4%All others 12.6%
Finding 07
38%
of AI Overview citations come from pages in the top 10
Ahrefs found 37.9% across 4M cited URLs, down from about 76% in its July 2025 study, though the method changed.[8] Ranking well helps, but is no longer the main route in.
See the dataFinding 08
80%
of AI crawling is for training, which sends almost no visitors back
Cloudflare’s data: 80% training, 18% search, 2% user actions. In July 2025 Anthropic’s crawlers made 38,066 requests per referred visit, OpenAI’s 1,091 and Google’s 5.4.[9]
See the dataFinding 09
2.1%
of crawled sites have an llms.txt file, and it shows no citation effect
The Web Almanac found llms.txt on 2.13% of desktop sites;[10] SE Ranking found no link to AI citations across about 300,000 domains;[11] Google says no special files or markup are needed for AI features.[12]
See the dataFinding 10
48%
of mobile sites pass all three Core Web Vitals
Up from 32% in 2021, and 56% on desktop.[13] On the basics, 43% of home pages use JSON-LD and 67.7% of pages have a meta description.[10]
- Mobile, 202132%
- Mobile, now48%
- Desktop, now56%
EXPLORE
Industry by industry, two measures.
Switch between how often AI Overviews appear and how much traffic AI assistants send. Gaps are industries the source did not publish.
How often Google shows an AI Overview
Share of searches that trigger an AI Overview. Higher means more answers shown before the links.
- Health Care48.75%
- Financials25.79%
- Utilities25.4%
- Information Technology11.4%
- Consumer Staples6.82%
- Real Estate4.48%
- Communication ServicesNot stated in the source
- Consumer DiscretionaryNot stated in the source
- IndustrialsNot stated in the source
- MaterialsNot stated in the source
All industries combined: 25.11%
THE LIBRARY
Ten places to dig in.
What AI answers do to clicks
Click-through loss, zero-click searches and who still gets the visit, from five studies.
OpenAI Overviews by industry
How often Google shows them, in which industries, and why three studies give three numbers.
OpenAI referral traffic
How much traffic assistants send, from which engines, and how fast it is growing by sector.
OpenWho AI cites
The domains assistants quote, by industry, and how little it overlaps with the top 10.
OpenCrawlers, robots.txt and llms.txt
What AI bots take, what they give back, and which files matter.
OpenTechnical foundations
How the web actually looks: titles, schema, speed and Core Web Vitals, 2021 to 2025.
OpenAEO by industry
Which industries get the most from answer engine optimization, by the numbers.
OpenThe source library
Every study we use, graded, dated and linked.
OpenMethodology
How a number earns its place, and what we refuse to publish.
OpenCite and share
How to cite the Index, reuse a chart and report a correction.
Open
BY INDUSTRY
Your industry’s numbers, with the sources.
Sourced benchmarks for each industry we serve, plus what public data says about AI search in that industry.
- Law firmsRising, no exact figure · Law and government: AI Overview coverage
- Construction and remodelingDeloitte, Indeed, McKinsey, Wolters Kluwer, Siemens · Industrials: most-cited domains
- Financial advisors, wealth and investment firms25.79% · Financials: searches showing an AI Overview
- Business consulting and coachingSourced benchmarks and rules
- Dental and orthodontics48.75% · Health Care: searches showing an AI Overview
- Medical practices and clinics48.75% · Health Care: searches showing an AI Overview
- Nonprofits and charitiesSourced benchmarks and rules
- Engineering and architectureDeloitte, Indeed, McKinsey, Wolters Kluwer, Siemens · Industrials: most-cited domains
- E-commerce6.82% · Consumer Staples: searches showing an AI Overview
- Local businessesSourced benchmarks and rules
- Home services and tradesSourced benchmarks and rules
- SaaS and software2.80% · IT: AI referral share of website traffic
- Accounting and taxSourced benchmarks and rules
- Marketing and creative agenciesSourced benchmarks and rules
- IT services and cybersecuritySourced benchmarks and rules
- Real estate and property managementSourced benchmarks and rules
- Manufacturing and industrialSourced benchmarks and rules
- Travel and toursSourced benchmarks and rules
- Education and trainingSourced benchmarks and rules
- Med spa, beauty and wellnessSourced benchmarks and rules
- Security and safetySourced benchmarks and rules
- Media and publishingSourced benchmarks and rules
- Staffing and HRSourced benchmarks and rules
- InsuranceSourced benchmarks and rules
- Events, venues and entertainmentSourced benchmarks and rules
- Agriculture and food productionSourced benchmarks and rules
- Biotech, pharma and medical devicesSourced benchmarks and rules
- Logistics, auto and equipmentSourced benchmarks and rules
- Restaurants and hospitalitySourced benchmarks and rules
- Fitness and sportsSourced benchmarks and rules
- Banking, lending and mortgageSourced benchmarks and rules
- Energy, utilities and environmentalSourced benchmarks and rules
- Healthcare services and senior careSourced benchmarks and rules
- Government and associationsSourced benchmarks and rules
- Pets and animalsSourced benchmarks and rules
WHAT THE RESEARCH SAYS WORKS
Get cited, not just ranked.
The first formal study of optimizing for AI answers, from researchers at Princeton and others, reported visibility gains of up to 40% in generative engine responses, and noted the effect varies by domain.[14]
Google’s own guidance says there are no extra requirements to appear in AI Overviews or AI Mode, no special schema and no new file formats: be indexable and publish helpful, people-first content.[12] And with only 38% of citations coming from the top 10, being the clearest source on a topic matters as much as rank.[8]
Business owners
Find your industry, see what AI search is doing to your clicks and what is worth doing first.
Agencies
Cite the numbers, download the data and reuse charts with credit. Every figure links to its source.
Journalists and analysts
Press-ready numbers with methods, sample sizes and caveats. Ask us for a quote or a custom cut.
OUR INTERPRETATION
What we make of the evidence, in one page.
The findings are the studies’. This reading is ours, kept separate so you can weigh it for yourself.
Webtec Research
Our interpretation
- Kris GjorgjioskiKeyword research and benchmarks
- Hristijan NajcheskiTechnical SEO, data checks
- Figures: the cited studies
- Reading: ours
The figures on this page come from the cited studies. This reading of them is ours, and you may weigh it differently.
Across the studies, three things hold. AI answers reduce clicks where they appear. Their reach varies enormously by industry. And who gets cited changes faster than most rankings do.
The practical consequence is that no single number describes your situation. Your industry’s exposure, the shape of your customers’ questions and your own foundations decide how much of this matters to you, and the case files show how those combine for ten industries.
- Measure informational and decision queries separately
- Track AI referrals and citations next to organic traffic
- Re-check the numbers every quarter, they move quickly
USE IT
Cite it. Share it. Check it.
The Index is built to be referenced. Copy a citation, download a chart’s data, or read how we grade sources. Found something wrong? Tell us and we will fix it in public.
Cite and shareCITE THIS PAGE
Webtec Research. (2026, October 15). The Open Index by Webtec: AI search and SEO benchmarks. The Open Index by Webtec. https://www.trywebtec.com/resources/index/
QUESTIONS
Questions about the Open Index.
What it is, who it is for, how we work, and how to use the numbers.
What is the Open Index?
The Open Index is Webtec Research’s public library of benchmarks on how AI search and answer engines treat different industries. It pulls together 19 published studies, explains what each finding means in plain English, compares industries and links every number to its source. It is managed by our research team, led by Kris, and checked by Hristijan.
Can I cite it or reuse a chart?
Yes. Every page has a “cite this page” box with APA, MLA, BibTeX and HTML formats, and every chart has a CSV download. Please link back to the page and credit Webtec Research. Our cite and share page has the details.
Why do you show studies that disagree?
Because they do, and hiding it would mislead. Studies measure different keyword sets, periods and definitions. We show each number with its method and explain the gap, so you can pick the study that matches your question.
How do you choose and grade sources?
We read each figure on the source’s own page. Grade A is independent, official or peer-reviewed. Grade B is a vendor or agency study with a disclosed method. We exclude numbers we could only find in secondary articles, single-site case studies and claims without a traceable dataset.
Does the Index include Webtec’s own data?
Webtec Research also studies what we see managing AEO and SEO programmes. We release those findings only when they are anonymised, aggregated, approved and verified. None are in this edition. Everything here comes from published, cited sources.
How often is it updated?
The Open Index is refreshed quarterly, in January, April, July and October. At each refresh we re-check every source, add new studies, retire outdated ones and record changes in the correction log on the methodology page. Each page shows the date it was last updated, and this is Edition 1 (October 15, 2026). The next edition is due in January 2027.
Who is the Open Index for?
Business owners who want to know how AI search affects their industry, marketers and agencies who need numbers they can cite, and journalists and analysts looking for a single place that compares the major studies. Each page is written so a non-specialist can follow it, and each figure links to its source for those who want to check.
Why does Webtec publish benchmarks?
Because decisions about AI search are being made on weak evidence. Studies are scattered, they disagree, and most are written for specialists. We bring them together, explain the differences and show where evidence is thin. It also demonstrates how we work: sourced, dated and open to correction.
SOURCES
Sources and notes
19 sources on this page: 8 independent or official (grade A) and 11 vendor or agency studies with a disclosed method (grade B). Numbers in brackets in the text match the numbers below. We read every figure on the source’s own page. How we grade sources.
- What we use:
- The first measurement of click loss for the top result when an AI Overview appears.
- Period:
- March 2024 vs March 2025
- Sample:
- 300,000 keywords: 150,000 with an AI Overview and 150,000 informational keywords without one.
- Read with care:
- Desktop CTR, informational keywords, from Google Search Console data. Correlation, not proven cause.
- What we use:
- The re-run: 58% lower top-result CTR, and the loss by position from 1 to 10.
- Period:
- December 2023 vs December 2025
- Sample:
- 300,000 keywords (150,000 with an AI Overview, 150,000 without), Google Search Console data.
- Read with care:
- Desktop only; keywords grouped by their December 2025 AI Overview status; correlation, not proven cause.
- Independent researchGrade APublished 2025-07-22Read the source
- What we use:
- Click and session behaviour with and without AI summaries; share of searches with a summary; which sources summaries cite.
- Period:
- March 2025
- Sample:
- 900 US adults tracked in KnowledgePanel Digital; 68,879 Google searches.
- Read with care:
- A US panel; does not measure publisher revenue.
- What we use:
- The share of Google searches that end without a click, and clicks to the open web per 1,000 searches.
- Period:
- Sept 2022 to May 2024 (mobile from Jan 2024)
- Sample:
- A US and EU clickstream panel; no sample size stated.
- Read with care:
- The authors say voice and the Google app are not captured, so zero-click is likely under-counted. The post links to a newer study.
- What we use:
- AI Overview prevalence and AI referral share by industry; ChatGPT’s share of AI referrals; most-cited domains by industry.
- Period:
- May to Sept 2025 (AI Overviews: Sept 15 to Oct 12, 2025)
- Sample:
- 13,770 enterprise domains in 10 industries; 17M AI responses and 100M+ citations; AI referral data from 1,215 domains (3.3B sessions, 35.7M AI sessions); 21.9M US Google searches for AI Overviews.
- Read with care:
- US data. AI Mode traffic is excluded because Google Analytics groups it with organic Google traffic. Some figures appear twice with different rounding; we use the more precise one.
- Vendor studyGrade BPublished 2025-12-15Read the source
- What we use:
- AI Overview prevalence over time and by category.
- Period:
- January to November 2025
- Sample:
- 10M+ keywords for prevalence over time; industry figures are the share of each industry’s keywords that show an AI Overview.
- Read with care:
- The page gives exact figures for only some categories and contradicts itself on Health.
- Independent researchGrade APublished 2025-06-25Read the source
- What we use:
- How many people use ChatGPT, by age and education.
- Period:
- Feb 24 to March 2, 2025
- Sample:
- 5,123 US adults, American Trends Panel, weighted to the adult population.
- Vendor studyGrade BPublished 2026-03-02Read the source
- What we use:
- How many AI Overview citations come from pages ranking in the top 10.
- Period:
- AI Overviews as of January 2026
- Sample:
- 863,000 keyword SERPs and 4M AI Overview URLs (Ahrefs Brand Radar).
- Read with care:
- Parsing method changed since the 2025 study, so the comparison is not like-for-like.
- Platform dataGrade APublished 2025-08-29Read the source
- What we use:
- Crawl-to-referral ratios by platform and the purpose of AI crawling.
- Period:
- January to July 2025 (purposes: past 12 months)
- Sample:
- Cloudflare Radar crawl and referral data; referral data comes from news-related customers.
- Read with care:
- Purpose classification relies on operator disclosures; referral data may not represent the wider web.
- What we use:
- How common titles, descriptions, canonicals, structured data, robots.txt and llms.txt are across the web.
- Period:
- 2025 crawl
- Sample:
- A crawl of millions of public websites; figures are for desktop and mobile pages.
- Read with care:
- Last updated 2026-06-09.
- Vendor studyGrade BPublished 2025-11-07Read the source
- What we use:
- llms.txt adoption among a sample of domains, and the lack of a measurable citation effect.
- Period:
- 2025
- Sample:
- About 300,000 domains; Spearman correlation, XGBoost and SHAP analysis.
- Read with care:
- The authors say results are context-dependent and may be outdated within weeks.
- What we use:
- What Google says is and is not required to appear in AI features.
- Period:
- Documentation, last updated Dec 10, 2025
- Sample:
- Google’s own guidance for AI Overviews and AI Mode.
- What we use:
- Core Web Vitals pass rates, 2021 to 2025, by device and page type.
- Period:
- CrUX July 2025
- Sample:
- Chrome UX Report field data plus HTTP Archive lab data across public websites.
- Read with care:
- Last updated 2026-05-05.
- What we use:
- The first formal study of optimizing for generative engines; reports visibility gains of up to 40%.
- Period:
- v3 revised June 28, 2024
- Sample:
- GEO-bench, a benchmark of diverse queries across domains.
- Read with care:
- The authors note efficacy varies across domains.
- Vendor studyGrade BPublished 2025-11-10Read the source
- What we use:
- Which domains AI assistants cite most, and how fast that mix changed.
- Period:
- July 14 to Oct 12, 2025 (13 weekly snapshots)
- Sample:
- 230,000+ prompts and 100M+ AI citations across ChatGPT search, Google AI Mode and Perplexity.
- Read with care:
- Most shares appear only in charts; we use the figures given in the text.
- What we use:
- None of the major AI crawlers it studied render JavaScript.
- Period:
- 2024
- Sample:
- Crawler request logs across Vercel’s network.
- Agency studyGrade BPublished 2025-11-04Read the source
- What we use:
- Organic and paid CTR with and without AI Overviews, and the effect of being cited.
- Period:
- June 2024 to September 2025
- Sample:
- 3,119 informational and educational search terms across 42 organizations; 25.1M organic and 1.1M paid impressions.
- Read with care:
- Retrospective cohort; paid sample is small; the page has small internal inconsistencies, so we use the Q3 2025 averages and endpoint values.
- Platform dataGrade BPublished 2025-03-17Read the source
- What we use:
- Growth of AI referral traffic by sector, and how AI-referred visits behave.
- Period:
- Nov 2024 to Feb 2025
- Sample:
- More than 1 trillion visits to US retail sites; a survey of 5,000+ US respondents.
- Read with care:
- Measures clicks on AI links only. Engagement and bounce are not defined on the page.
- Vendor studyGrade BPublished 2025-11-13Read the source
- What we use:
- Sub-industry AI referral share and AI Overview prevalence for technology.
- Period:
- May to Sept 2025
- Sample:
- The IT industry and three sub-industries, from the same dataset as the main report.
Preferred sources on Google
Make Webtec a preferred source on Google.
Pick us once, and Google shows you more of our research and guides in Top Stories when we publish. It takes one click and you can change it at any time.
A LIVING REFERENCE
Refreshed every quarter.
We re-check every source in January, April, July and October, add new studies and retire old ones. This is Edition 1 (October 15, 2026); the next is due January 2027. Changes are logged on the methodology page.
