CheckAIContent is a web-based tool designed to detect text generated by artificial intelligence models such as ChatGPT, Gemini, and Claude. It analyzes written content to estimate the probability of AI involvement, using sentence-level scoring and highlights to indicate AI-like writing patterns. The tool is available for free and does not require user registration or payment. The tool includes several features beyond detection. An AI Paragraph Rewriter allows for goal-driven rewrites to make text clearer, shorter, or sharper while preserving meaning. An AI Tone Changer adjusts the voice of content for professional, friendly, formal, casual, or other tones. A Grammar Checker provides spelling, grammar, and style suggestions with support for US, UK, and other English variants. Users can analyze content by pasting text or uploading DOCX or PDF files. The detection engine examines sentence structure, perplexity, burstiness, and linguistic patterns to generate an AI probability score and detailed authenticity insights. The tool is designed with privacy in mind, as content is not stored or shared. It is commonly used by teachers, writers, and SEO professionals to verify content originality.