An AI search engine answers your question in writing instead of handing you a list of links, and the good ones show where the answer came from. This guide compares 9 of them: what each searches, how it cites, what it costs and how many people use it, with every figure sourced and marked when it could not be read on the company’s own page.
Google’s figures are from its own announcements[1][2]; ChatGPT’s is OpenAI’s announcement as reported[12]. Weekly and monthly users are not directly comparable.
What an AI search engine is
An AI search engine runs a search, reads the results and writes an answer, usually with links to the pages it used. The part that differs most between them is the first step: whose index they search. Perplexity says its crawler, PerplexityBot, surfaces and links websites in its results[5]; OpenAI runs OAI-SearchBot to surface sites in ChatGPT search[6]; Google’s AI Mode runs many searches of Google’s own index at once, which Google calls query fan-out[7]; and Copilot Search runs on Bing[9].
Find the right AI search engine
- 1PerplexityPerplexity AI2 of 2The most citation-forward: every search answer links its sources inline.Searches: Its own crawler, PerplexityBot, and indexSources: Numbered citations on every search answerFree: Free planPaid: Pro about $20/monthreportedScale: 780M queries in May 2025reported · CEO, reported by TechCrunch, 5 Jun 2025
- 2ChatGPT searchOpenAI2 of 2The assistant most people already use, with search built into the Free plan.Searches: OpenAI's own crawler (OAI-SearchBot) plus search partnersSources: Inline citations and a Sources panel when it searchesFree: Search included on the Free planPaid: Go, Plus and Pro plansScale: 900M+ weekly users, Feb 2026reported · OpenAI announcement, reported by Search Engine Land, 27 Feb 2026
- 3Google AI ModeGoogle2 of 2Google's own results, researched with many searches at once, at no cost.Searches: Google Search's index, with query fan-outSources: Links and source cards alongside the answerFree: Free inside Google SearchScale: 1B+ monthly active users · Sundar Pichai, Google I/O, 19 May 2026
- 4Microsoft CopilotMicrosoft2 of 2Built on Bing, inside Windows and Edge, and the only one with a citation report for site owners.Searches: Bing's indexSources: Cites sources prominently in Copilot SearchFree: Free consumer app
- 5ClaudeAnthropic2 of 2Careful, well-cited answers, with web search on every plan including Free.Searches: Web search, reportedly powered by BraveSources: Direct citations in search answersFree: Web search included on the Free planPaid: Pro $20/month, or $17/month billed yearly
- 6Brave Search (Ask Brave)Brave2 of 2An independent index that is neither Google nor Bing, from a privacy-focused company.Searches: Brave's own independent indexSources: AI answers grounded with citationsFree: Free, in any browserScale: 15M+ AI answers a day · brave.com, 29 Sep 2025
- 7Gemini appGoogle1 of 2Google's assistant, grounded in Google Search, with deep research on the free tier.Searches: Grounded in the Google Search indexSources: A Sources button, but not every answer has sourcesFree: Free tier, including Deep ResearchPaid: Google AI Ultra from $100/monthScale: 1B+ monthly users · blog.google, 11 Aug 2026
- 8GrokxAI1 of 2The one to use when what people are posting right now matters.Searches: Real-time web and posts on XSources: Links to web pages and X postsFree: Free tierPaid: SuperGrok plansreported
- 9DeepSeekDeepSeek1 of 2A free assistant with optional web search, from a Chinese AI lab.Searches: Web search with an undisclosed providerSources: Citations when its search toggle is onFree: Free web chat and apps
The AI search engines compared
| Searches | Shows sources | Free tier | |
|---|---|---|---|
| Perplexity | Its own crawler, PerplexityBot, and index | ✓Yes | ✓Yes |
| ChatGPT search | OpenAI's own crawler (OAI-SearchBot) plus search partners | ✓Yes | ✓Yes |
| Google AI Mode | Google Search's index, with query fan-out | ✓Yes | ✓Yes |
| Gemini app | Grounded in the Google Search index | ~ | ✓Yes |
| Microsoft Copilot | Bing's index | ✓Yes | ✓Yes |
| Claude | Web search, reportedly powered by Brave | ✓Yes | ✓Yes |
| Brave Search (Ask Brave) | Brave's own independent index | ✓Yes | ✓Yes |
| Grok | Real-time web and posts on X | Varies | ✓Yes |
| DeepSeek | Web search with an undisclosed provider | Varies | ✓Yes |
Who uses which AI search engine
There is no official league table. Two trackers publish shares, and they disagree, because they measure different things. Similarweb counts visits to each assistant’s website; StatCounter measures something else and does not publish its method on the page. Read them as two views, not one truth.
| ChatGPT | 55.5% |
|---|---|
| Gemini | 25.6% |
| Claude | 9.3% |
| DeepSeek | 3.4% |
| Grok | 2.4% |
| Copilot | 1.6% |
| Perplexity | 0.9% |
| ChatGPT | 79.40% |
|---|---|
| Gemini | 10.90% |
| Perplexity | 4.31% |
| Copilot | 2.79% |
| Claude | 2.57% |
Sources: Similarweb via The Decoder[3] and StatCounter[4]. Perplexity’s share differs roughly fivefold between them.
The best free AI search engines
Free is the norm among AI search tools: if you want an AI search engine free of charge, you have plenty of choice. ChatGPT lists search on its Free plan, Claude includes web search on Free[10], Google AI Mode is part of Google Search, the Gemini app has a free tier, and Ask Brave is free in any browser[11]. Paid plans mostly buy higher limits, newer models and longer research runs, not the ability to search.
Perplexity alternatives
People looking for a Perplexity alternative usually want one of three things it does well. For sources on every answer, try Google AI Mode or Claude. For an index that is not Google’s, try Brave. For long research reports, try the Gemini app’s Deep Research. The Perplexity SEO guide covers how Perplexity picks what it cites.
What this means for your brand
Each engine reads a different index and cites differently, so being visible in one does not mean being visible in all. A page Bing has not indexed cannot appear in Copilot; a site that blocks PerplexityBot will not be linked in Perplexity; and Google’s AI features follow Google’s own indexing rules.
The guides to ChatGPT SEO, Google AI Mode, Gemini SEO, Copilot SEO and Claude SEO cover each engine in depth. To check which AI crawlers your site lets in, use the AI Crawler Checker.
Questions people ask
What is the best AI search engine?
It depends on what you need. Perplexity shows sources on every search answer and has its own index. Google AI Mode brings Google's results with many searches at once. ChatGPT search is the one most people already use. Brave has an independent index. Use the picker on this page to rank them by what matters to you.
What is the best free AI search engine?
Most AI search engines have a free tier. ChatGPT includes search on its Free plan, Claude includes web search on its Free plan, Google AI Mode is free inside Google Search, the Gemini app has a free tier with Deep Research, and Ask Brave is free in any browser.
What is the best alternative to Perplexity?
For always-visible sources, Google AI Mode and Claude are the closest. For an independent index, Brave Search. For the largest user base and search on a free plan, ChatGPT. For Google-grounded research reports, the Gemini app's Deep Research.
Do AI search engines use Google?
Some do. Google AI Mode, AI Overviews and the Gemini app use Google's index. Microsoft Copilot uses Bing. Perplexity and Brave run their own crawlers and indexes, and OpenAI runs OAI-SearchBot for ChatGPT search. Claude's search is reportedly powered by Brave.
Which AI search engine is most accurate?
No independent study settles it, and accuracy varies by question. What you can check is whether an engine shows its sources: an answer with citations lets you verify it, and one without asks you to trust it.
How many people use AI search?
Google says AI Overviews has over 2.5 billion monthly users and AI Mode over 1 billion, and the Gemini app passed 1 billion monthly users in August 2026. OpenAI reported more than 900 million weekly ChatGPT users in February 2026. Most other companies do not publish user figures.