Explain This

Highlight text for instant AI explanations and translation—50 free AI requests daily, no login, no bulky sidebar or tab switching. Explain This is a focused AI reading assistant for people who want help with the text in front of them without copying it into a chatbot, switching tabs, or opening a bulky sidebar.

Primary proof points:

• Highlight-first explanations and translation that preserve reading flow
• 50 free built-in AI requests each day, with no account or API key required
• A small on-page action bubble instead of a persistent sidebar
• Explain, translate, cultural context, fact-check, and source-tracing actions
• Concise or detailed responses in English or Chinese
• Optional BYOK for OpenAI, Gemini, and DeepSeek

Do not describe the extension as a PDF reader. Chrome's built-in PDF viewer is not a normal webpage and the selection tool is not guaranteed to run there.

Explain This 是一款轻量级 AI 划词翻译与阅读助手：在网页选中文字，即时解释、 翻译、补充文化语境、事实核查或追溯出处，无需复制粘贴，也没有常驻侧边栏。

它适合阅读英文文章、技术文档、在线论文页面和其他高密度网页内容；遇到单词、 长句或段落时，可以在原处选择需要的理解方式，然后继续阅读。