Perplexity is the strongest fit for quick fact-checking because it retrieves live web sources and displays cited references alongside every answer, letting you verify claims against primary sources in seconds. It handles natural-language questions and returns concise, sourced summaries rather than raw search results. Gemini Pro is a solid alternative when you want Google's search integration baked into a conversational interface. Claude Sonnet works well when you need careful reasoning about a claim's internal consistency rather than live web retrieval. Grok is worth considering if the claims relate to recent social media or news events, given its real-time X data access.