From side project to writing giant
QuillBot was founded in 2017 in Chicago by Rohan Gupta, Anil Jason, and David Silin, who built an NLP-powered paraphrasing tool that exploded with students and professionals long before ChatGPT made AI writing mainstream. The company raised a $4.25M seed led by Sierra Ventures and GSV Ventures, then was acquired in August 2021 by Course Hero — now Learneo — where Gupta leads the writing vertical spanning QuillBot, LanguageTool, and Scribbr.
A full AI writing suite
Today QuillBot goes far beyond paraphrasing: it offers a grammar checker, summarizer, translator, AI detector, plagiarism checker, citation generator, AI chat, humanizer, and even PDF and presentation tools. Its Chrome extension alone counts more than 6 million users with a 4.7/5 rating, and apps cover Edge, Safari, Word, iOS, Android, Windows, and macOS — meeting writers wherever they type.
Freemium at scale
A generous free tier handles everyday paraphrasing and grammar checks, while Premium unlocks unlimited paraphrasing modes, faster processing, advanced AI features, and plagiarism checking. Its blend of utility and accessibility has made QuillBot one of the most-used AI writing products in the world, particularly among students and non-native English speakers.