QuillBot is an AI-powered writing and paraphrasing platform that helps students, professionals, and content creators improve, rephrase, and refine their written content. Founded in 2017 by Anil Jason, Rohan Gupta, and David Silin, the company was headquartered in Chicago, Illinois, and was acquired by Course Hero in 2023. QuillBot's flagship Paraphraser tool uses advanced natural language processing to rewrite sentences, paragraphs, and entire documents while preserving the original meaning, offering multiple rewriting modes including Standard, Fluency, Formal, Simple, Creative, Expand, and Shorten to match different writing contexts and style preferences. The Grammar Checker analyzes text for grammatical errors, punctuation mistakes, spelling issues, and stylistic improvements, providing real-time suggestions with explanations. QuillBot's Summarizer condenses long texts, articles, and documents into concise summaries in either key sentences or paragraph format, making it useful for research and study workflows. The platform includes a Citation Generator that creates properly formatted citations in APA, MLA, Chicago, and other academic styles from URLs, book titles, or DOIs. QuillBot also offers a Translator that supports over 30 languages, a Plagiarism Checker that scans text against web sources and academic databases, and a Co-Writer that combines all tools into a unified writing workspace. The platform is available as a web application, browser extensions for Chrome and Firefox, desktop applications, and integrations with Microsoft Word and Google Docs. QuillBot operates on a freemium model with a free tier that provides access to basic paraphrasing with word limits and limited mode options. The Premium plan is priced at approximately $9.95 per month and unlocks unlimited paraphrasing, all rewriting modes, advanced grammar checking, increased plagiarism checking, and faster processing. Team plans are available for organizational deployment.

AI Content Detectors

QuillBot includes a Plagiarism Checker that scans written content against web sources and academic databases to identify potential duplication and ensure content originality. The tool highlights matching passages with source links and match percentages, making it valuable for students, academics, and content creators who need to verify the uniqueness of their work.

AI Grammar Checkers

QuillBot's Grammar Checker uses AI to detect and correct grammatical errors, punctuation mistakes, spelling issues, and stylistic inconsistencies in real time. The tool provides detailed suggestions with explanations for each correction, helping users not only fix errors but also understand the underlying grammar rules.

AI Paraphrasers

QuillBot is one of the most widely used AI paraphrasing tools, offering seven distinct rewriting modes including Standard, Fluency, Formal, Simple, Creative, Expand, and Shorten. The paraphraser rewrites text while preserving original meaning, enabling users to rephrase sentences and entire documents to avoid repetition, improve clarity, or adjust tone and style.

AI Summarizers

QuillBot's Summarizer condenses long articles, research papers, and documents into concise key sentences or paragraph summaries. Users can adjust the summary length and choose between extractive summaries that highlight the most important sentences or abstractive summaries that generate new condensed text capturing the core ideas.

AI Writing Tools

QuillBot functions as a comprehensive AI writing assistant with its integrated Co-Writer workspace that combines paraphrasing, grammar checking, summarization, and citation generation into a unified writing environment. The platform helps writers at every stage from drafting to final polishing, with browser extensions and word processor integrations for seamless workflow.