Ahrefs Research | AI Information Sources Changed in 6 Months: Latest Ranking of Domains Cited by ChatGPT, AI Mode, AI Overviews, Perplexity, and Copilot

Do you know which sites AI considers 'reliable sources' when generating answers?

With Google's AI Overviews, AI Mode, ChatGPT, Perplexity, and Copilot, AI is now at the center of the search experience. In this context, 'being cited by AI' is becoming a new metric directly linked to brand and content exposure.

This time, Ahrefs used its proprietary AI search visibility tool, 'Brand Radar,' to analyze citation data across five AI platforms and reveal the TOP 10 domains most trusted by AI. Furthermore, considering that approximately six months have passed since the previous survey published in October 2025, we also examine how AI's citation trends have changed.

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▪️ Overall Ranking: TOP 10 Domains Cited by AI

Below is the overall ranking, aggregating citations from five AI platforms (cumulative as of March 31, 2026).

The overall 1st place is YouTube (3,318,795 citations), cited by three LLMs: AI Mode, AI Overviews, and Perplexity. 2nd place, Wikipedia Japanese version (978,834 citations), appeared in four LLMs, making it the most frequently appearing domain.

Notably, 5th place, note.com (384,517 citations), is consistently cited by four LLMs.

On the other hand, 3rd place, Google (906,952 citations), and 6th place, Amazon.co.jp (360,091 citations), appeared in only one LLM (AI Mode) respectively, indicating that their citations are concentrated in specific AIs.

Furthermore, 9th place, PR TIMES (95,655 citations), is noteworthy for ranking despite being cited only by ChatGPT, indicating that press releases are recognized as 'official information' by AI.

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▪️ 'Personalities' of Each AI Visible by Platform

We have organized the differences in citation trends for each AI, which are not apparent from the overall ranking alone, by platform. Detailed rankings and analysis for each platform are explained in this blog post.

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▪️ 6 Months Since the Last Survey: What Has Changed?

For this survey, Ahrefs published an article in October 2025 titled "Thorough Comparison of Japanese Information Sources for AI Search Engines." At that time, the survey targeted ChatGPT, AI Mode, Copilot, and Perplexity LLMs, analyzing data from May to September 2025. This time, we compare the data from the subsequent six months (December 2025 to March 2026) to examine how AI's citation trends have changed.

Biggest Change: The 'Disappearance' of Reddit and Yahoo! Chiebukuro

The most striking finding of the previous survey was that ChatGPT cited Reddit as the overwhelming No. 1 (228,388 citations). However, this time, Reddit has disappeared from ChatGPT's top 5. Similarly, Yahoo! Chiebukuro, which was No. 1 for Perplexity in the previous survey (518,977 citations), has also disappeared from the top 5 of both platforms.

Possible factors behind this change include a review of the freshness and reliability scores of content sources in each AI.

Three Key Points from 6 Months of Data

① AI citation trends can change significantly in a short period: The fact that Reddit disappeared from ChatGPT's top and Yahoo! Chiebukuro disappeared from Perplexity's top indicates that being 'cited by AI now' is not necessarily permanent.

② note.com and ameblo.jp are stable AI trusted sources: Both platforms appeared in the top ranks of multiple AIs in both the previous and current surveys, consistently evaluated as Japanese content.

③ The value of press releases (prtimes.jp) is maintained: The presence of prtimes.jp in ChatGPT has been stable in the top ranks in both previous and current surveys, demonstrating that PR activities continue to influence AI citations.

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▪️ Implications for SEO and PR Strategies in the AI Era

The results of this survey provide important implications for information dissemination strategies in the AI search era. Continuously publishing content on domains cited by AI is becoming an effective means to increase exposure via AI. Furthermore, as this survey confirmed that citation trends can change in a short period, establishing a system to regularly monitor your brand's AI citation status with dedicated tools like Ahrefs Brand Radar is indispensable for brand strategy in the AI era.

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▪️ What is Ahrefs Brand Radar?

All data in this article was obtained from Ahrefs Brand Radar. Brand Radar is a tool that allows real-time tracking of brand mentions, citations, and impressions across multiple AI platforms such as ChatGPT, Perplexity, and Google AI. It can be used to understand how much your brand and competitors are cited by AI and to formulate information strategies for the AI era.

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▪️ About Ahrefs

Ahrefs Pte. Ltd. (Ahrefs) develops and provides "Ahrefs," an all-in-one marketing tool that collects and analyzes accurate and fresh data using its world-leading proprietary crawler and data technology. It primarily features world-leading SEO analysis functions and covers marketing functions such as AI search analysis, AI content creation, web traffic analysis, and SNS posting. Used by users in over 180 countries worldwide, it supports the planning and execution of effective data-driven marketing strategies, from competitive analysis to content strategy.

Official website: https://ahrefs.com/ja/

Japanese blog: https://ahrefs.com/ja/blog

Official X account: https://x.com/AhrefsJP

Evolve Singapore 2026: https://ahrefsevolve.com/singapore/

Survey Overview

Analysis targets: AI Mode (Google), AI Overviews (Google), ChatGPT, Perplexity, Copilot

Data period: December 2025 - March 31, 2026 (cumulative)

Aggregation metric: 'Number of Citations' in each AI's response

Tool used: Ahrefs Brand Radar

Detailed blog article: "TOP 10 Domains Most Trusted by AI [Latest Edition April 2026] Analyzed with Ahrefs Brand Radar"