If you came here to list the top international SEO agencies, pause. That search is already outdated unless the agency is built for AI search, zero-click visibility, and global brands that need citations as much as rankings. The numbers are blunt: Gartner projects a 25% decline in traditional search by 2026, AI search queries now total 6–7 billion per month and are growing 40–50% year-over-year, ChatGPT has 900M+ weekly active users, Perplexity processes 100M+ queries per week, 28–30% of the US population already uses AI search, and 60% of Google searches end without a click. The agency checklist below is the real answer to which international marketing agencies specialise in SEO now.
AI search engines have moved from novelty to structural search infrastructure. That shift changes how global brands choose partners. ChatGPT grew from 200M+ weekly users in 2024 to 550M+ in 2025 and now has 900M+ weekly active users, with +45% YoY growth and 340% YoY query growth. It handles 250–500M search-intent queries per week and ~4 billion queries per month, while also reaching 700M+ weekly active users across all use cases.
Perplexity followed a similar arc: 40M MAU in 2024, 75M in 2025, and 140M+ in 2026 estimated, with +87% YoY growth and 3–4x year-over-year expansion. It processes 50M weekly queries in 2026, 100M+ queries per week currently, 1.2B+ monthly queries, and roughly ~1.2B annualized queries. Google AI Overviews launched in Q2 2024, accounted for 30% of Google queries in 2025, is projected to hit 50%+ in 2026, and already processes ~2.5 billion queries per month. AI Mode has 200M+ monthly active users.
| Platform | Current or Recent Scale | Key Growth Signal |
|---|---|---|
| ChatGPT | 900M+ weekly active users | +45% YoY; 340% YoY query growth |
| Perplexity | 100M+ queries per week | 3–4x year-over-year growth; +87% YoY |
| Google AI Overviews | ~2.5B queries per month | 30% of Google queries in 2025; 50%+ projected in 2026 |
| Microsoft Copilot | 33M active users, 20M paid | +67% YoY; 64% enterprise/workplace usage |
The broader scale matters too. Traditional Google still processes 8.5B searches per day, or about 50B weekly, while AI search handles about 250M queries per day. That means AI search is still only about ~2% of traditional Google volume, but it is growing much faster: 40–50% YoY versus Google’s 5–10%. Google still holds ~80% of global query volume in 2026, especially on transactional and navigational searches, but the disruption is concentrated on informational queries. By the end of 2027, AI search share is projected to reach 20–25% of total query volume, informational queries will trigger AI answers in over 50% of cases, and non-branded informational click volume is projected to decline 35% versus 2024 baselines. Growth trajectories may cross in 2028–2029.
Bottom line: the agency you choose must treat AI search not as a side project, but as the core of international visibility.
Adoption is already broad enough to matter commercially. In the US, 28–30% of the general population uses AI search, and 67% of knowledge workers do as well. That is not an edge case. It is a mainstream behavior in the audiences that shape B2B and high-consideration buying.
The age curve is even sharper. Users aged 18–24 show 67% AI search adoption, 25–34 sit at 52%, 35–44 at 38%, 45–54 at 22%, and 55+ at 12%. Frequency follows the same pattern: 46% of people aged 18–29 use AI weekly, ages 25–34 use it 3–4x/week, and ages 35–44 use it 1–2x/week. Education correlates strongly too, with 15% adoption among high school graduates, 48% among college graduates, and 62% among those with graduate degrees.
Regional differences are significant, which is exactly why an international SEO partner needs local AI-search literacy. Western Europe sits at 24%, East Asia at 28%, China at <3%, India at 8%, Latin America at 12%, and the Middle East & Africa at 5%. In B2B and knowledge-heavy industries, adoption rises to 50–60%. An agency that cannot translate these regional and demographic patterns into content priorities is guessing.
AI search adoption in the US is 28–30%, and in Western Europe it is 24%; any global strategy that ignores that spread is incomplete.
AI search is not just informational; it is commercial. The query mix proves it. Across AI search, How-to/Tutorials account for 28%, Definition/Explanation 22%, Comparison/Analysis 18%, Brainstorming/Ideation 15%, Research/Current events 12%, and Troubleshooting/Debugging 5%. In other words, the top of the funnel is already inside AI surfaces.
ChatGPT Search shows the same pattern in a more monetizable form: 58% informational and research, 22% commercial investigation, 12% code and technical, 5% local and navigational, and 3% purely transactional. That means the brand missing from citations is missing during research, comparison, and shortlist formation. ChatGPT Search is specializing on the segment Google was least monetized for.
For global brands, this matters because commercial-investigation queries are where agency value becomes visible. If the content strategy cannot win in research mode, it will not win at decision mode. That is why an international SEO agency must know how to shape content for intent, not just keywords.
This is the new operating system. Traditional Google still has a 60% zero-click rate, but AI platforms push that behavior further. ChatGPT Search answers have an 82% zero-click rate and average 2–3 citations. Perplexity answers have a 93% zero-click rate and average 4–6 citations, giving it 2.1x higher citation density than ChatGPT Search. Google AI Mode answers have an 88% zero-click rate and average 3–5 cited sources.
AI Overviews appear on roughly 35% of informational queries and cause a 40–50% CTR drop on pages below them. Position one CTR drops from 31.7% to 19.8% when an AI Overview is present. Yet clicks that survive AI Overviews see a +23% conversion lift. That is the paradox: fewer clicks, but more qualified ones.
The trust and traffic economics are equally important. Consumer AI searches result in 15–20% click-through to sources, while enterprise searches see 30–40%. 25% of users who find a brand in Google AI click through to the site. Meanwhile, 15–20% of remaining search traffic is now going to AI platforms instead of blue links, consumers trust AI over search results at 42%, enterprise users trust AI but verify with sources at 58%, and AI-referred traffic converts 10–20% lower than Google search traffic even though the volume is additive. Optimized brands, however, can see 15–25% traffic increments from AI search visibility.
Platform citation patterns show where authority is won. For ChatGPT Search, citations are distributed across Reddit 18%, Wikipedia 12%, major news 11%, Stack Overflow/GitHub 8%, YouTube transcripts 6%, gov/academic 5%, product review 5%, and all other 35%. For Perplexity, the split is Reddit 11%, Wikipedia 9%, major news 16%, Stack Overflow/GitHub 10%, YouTube 4%, gov/academic 12%, product review 4%, and all other 34%. For Google AI Mode, the mix is Reddit 14%, Wikipedia 16%, major news 12%, Stack Overflow/GitHub 6%, YouTube 9%, gov/academic 7%, product review 6%, and all other 30%. Reddit has the highest citation share across AI search platforms, while Wikipedia is structurally important for definitions and entity anchoring.
Original data is cited at the highest rate per published piece, and content with direct-answer paragraphs is cited 2–3x more often than buried answers. That is why winning citations in Perplexity is a legitimate traffic strategy, not a vanity metric. The agency you select must be able to show how your brand will be cited in the right context on each platform.
AI search is a material channel. The click may be smaller, but the citation can be the new conversion path.
The decline is already visible across sectors. Non-branded informational query traffic is down 15–30% year over year across content sites. Transactional and branded query traffic has held up better than informational traffic, but the message is clear: informational discovery is the category under the most pressure.
Health and medical information sites have experienced -35% to -50% YoY organic traffic change. How-to and reference content sites are down -30% to -45%. Finance and investing publishers show -20% to -35%, tech news and analysis sites -15% to -25%, travel content sites -15% to -25%, eCommerce and marketplaces -5% to -15%, local services directories -5% to -10%, B2B SaaS product content -3% to -12%, and branded and direct-response sites are flat to +5%. That spread tells you exactly where AI disruption is hitting hardest.
These are not abstract trends. They are the operating conditions for global brands trying to keep international demand intact. If your agency cannot explain the vertical shifts and build a plan to protect your brand inside AI search, it is not the right partner for 2026.
Ask the question differently. Instead of “Which international marketing agencies specialise in SEO?” ask, “Which agencies can win in AI citation economy, zero-click environments, and global search markets at once?” The agencies that deserve the label are the ones capturing the 15–25% traffic uplift from AI search visibility, earning citations on Perplexity where 18–22% of cited sources get clicks, surviving Google AI Overviews where position one still converts 23% better after the click, and avoiding the -35% to -50% traffic crash hitting informational publishers.
ChatGPT Search is specializing on the segment Google was least monetized for. All leading AI search products have converged on agentic browse capability. Anthropic’s Claude has pushed browse and tool use. Those facts are exactly why a credible international SEO agency must already be designing for citations, source authority, and platform-specific visibility, not just rankings.
Use this as your RFP filter. These are the capabilities global brands should demand before they trust an agency with international growth.
Each of these items links directly back to the data. That is the point. A real international SEO agency does not present opinions; it presents evidence, coverage plans, and reporting that maps to the way people now search.
Stop searching for a generic list of agencies. With AI search growing 40–50% YoY and set to trigger answers on >50% of informational queries by 2027, the window is now. Traditional search decline is projected at 25% by 2026, and brands that delay will see their international funnel shrink. The agencies that win are the ones already delivering the 15–25% traffic uplifts that AI-optimized brands achieve while competitors lose 35%+.
If you want a partner built for that reality, explore International SEO Services and start with a team that already operates on this checklist. For global brands, that is the logical next step.
