QuillBot

QuillBot is an AI-powered writing assistant that specializes in paraphrasing, grammar checking, and text improvement, helping millions of users worldwide produce clearer, more polished writing. Acquired by Course Hero in 2023, QuillBot has become one of the most popular AI writing tools for students, academics, and professionals who need to rephrase content while maintaining meaning and improving readability. The platform's core Paraphraser tool offers seven distinct modes including Standard, Fluency, Formal, Simple, Creative, Expand, and Shorten, each transforming text in different ways to match the desired style and purpose. The Grammar Checker goes beyond basic spell-check to identify and fix complex grammatical errors, punctuation issues, and sentence structure problems with clear explanations of each correction. QuillBot's Summarizer condenses long articles, papers, and documents into concise summaries using either key sentence extraction or paragraph-style summarization. The Citation Generator supports MLA, APA, Chicago, and other academic citation formats, making it invaluable for research papers and academic writing. The Plagiarism Checker scans content against billions of web pages and academic databases to ensure originality, providing detailed reports with source identification. A Co-Writer feature combines all tools into a single writing environment where users can paraphrase, check grammar, and summarize without switching between tools. QuillBot integrates with Google Docs, Microsoft Word, and Chrome through browser extensions, fitting seamlessly into existing writing workflows. The free tier provides basic paraphrasing with word limits, while the Premium plan unlocks all seven paraphrasing modes, advanced grammar suggestions, and unlimited usage for serious writers.