# QuillBot
QuillBot is an AI-powered writing suite that lets users paraphrase text, check grammar, analyze tone, and improve fluency; it is owned by Learneo, the platform formerly called [Course Hero](https://www.edgepedia.org/course-hero). Founded in 2017 by students building a paraphraser to help ELL students, it has grown into a multi-tool product line spanning grammar checking, AI detection, plagiarism checking, translation and, more recently, audio, image, and search tools.
| Key fact | Detail |
|---|---|
| Founded | 2017, by Anil Jason, Rohan Gupta, and David Silin[1](https://quillbot.com/about) |
| Owner | Learneo, previously Course Hero[1](https://quillbot.com/about) |
| Core tools | Paraphraser, Grammar Checker, AI Detector, Plagiarism Checker, AI Humanizer, AI Image Generator[2](https://quillbot.com/) |
| Usage (vendor-reported) | Over 56 million monthly active users in the writing vertical; 5.3 billion annual Paraphraser inputs[1](https://quillbot.com/about) |
| Users (vendor homepage) | 35+ million users worldwide[2](https://quillbot.com/) |
| Mobile | AI keyboard app with 2 free and 8 premium paraphrase modes, translation in 40+ languages[3](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en) |
| AI detector accuracy | About 78–80% in testing cited by a 2026 review, with false positives on roughly one in five texts in the reviewer's own informal testing[4](https://plisio.net/ai/quillbot-ai) |
## What QuillBot is
QuillBot's central product is the Paraphraser, a tool that rewrites submitted text while attempting to preserve meaning. Around it, the company has assembled a suite marketed on its homepage: a Grammar Checker, an AI Detector for identifying AI-generated content, a Plagiarism Checker, an AI Humanizer that rewrites machine-sounding text, and an AI Image Generator, alongside tone analysis and fluency tools.[2](https://quillbot.com/) The suite is delivered through a website and a mobile app built around an AI keyboard.[2](https://quillbot.com/) • [3](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en)
One number does not match another: the company's own pages give different user counts. The About page says the writing vertical helped over 56 million monthly active users, while the homepage claims 35+ million users worldwide.[1](https://quillbot.com/about) • [2](https://quillbot.com/) The two figures may measure different things (a multi-product vertical versus the QuillBot brand alone), but the sources do not explain the gap, and no independent traffic verification appears in the available record.
## Launch history
QuillBot was founded in 2017 by [Anil Jason](https://www.edgepedia.org/anil-jason), Rohan Gupta, and [David Silin](https://www.edgepedia.org/david-silin). Jason wanted to build a tool to help ELL students, students learning English as a second language, with writing, and enlisted his friends Gupta and Silin to create the Paraphraser.[1](https://quillbot.com/about) The tool went viral on Reddit almost immediately after launch, and the three founders entered UIUC's iVenture Accelerator, where they won initial funding.[1](https://quillbot.com/about)
The company later became part of Learneo, previously known as Course Hero, which the vendor describes as a platform focused on productivity and learning; the acquisition activity formed a writing vertical that the company says served over 56 million monthly active users.[1](https://quillbot.com/about) Under CEO Andrew Grauer, QuillBot has expanded beyond writing into audio, image, and search tools.[1](https://quillbot.com/about)
## Features and platforms
The web suite covers the full writing workflow described on the homepage: paraphrasing, grammar checking, tone analysis, fluency improvement, AI detection, plagiarism checking, humanizing AI text, and image generation.[2](https://quillbot.com/)
The mobile product is an AI keyboard app. Its [Google Play](https://www.edgepedia.org/google-play) listing describes rewriting text for clarity, tone, and flow using 2 free paraphrase modes, with 8 premium paraphrase modes available to paying users; a translator covering 40+ languages including Spanish, French, German, and English; an AI detector; AI chat; and image generation.[3](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en) The free-versus-premium split on mobile, two modes free and eight paid, is the clearest published statement of what QuillBot paywalls; detailed web-tier pricing does not appear in the sources used here.
## By the numbers
All scale figures for QuillBot are vendor-reported; the available record contains no independent measurement of its traffic or installs.
- **56 million**: monthly active users served by Learneo's writing vertical, per the company's About page, following its 2022 acquisition activity.[1](https://quillbot.com/about)
- **35+ million**: users worldwide claimed on the product homepage.[2](https://quillbot.com/) This is the unresolved discrepancy noted above.
- **5.3 billion**: annual Paraphraser inputs cited by the company.[1](https://quillbot.com/about)
- **40+**: languages supported by the mobile translator.[3](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en)
- **2 free / 8 premium**: paraphrase modes on the mobile keyboard.[3](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en)
## Reception and the AI-detector reliability dispute
The most consequential independent-style finding concerns QuillBot's AI Detector. A 2026 review reports testing in which the detector achieves about 78% to 80% accuracy on AI-content detection benchmarks for text generated by tools such as ChatGPT, Claude, and Gemini.[4](https://plisio.net/ai/quillbot-ai) The same reviewer's informal testing found the detector flagged his own hand-written paragraphs as "likely AI" roughly one in five times, a false-positive rate he describes as capable of causing real panic for a student about to submit a paper.[4](https://plisio.net/ai/quillbot-ai)
That review's advice is to run the same text through multiple detectors, naming [GPTZero](https://www.edgepedia.org/gptzero), Originality.ai, and Turnitin, and treat the consensus as the verdict, because no single detector is reliable enough to bet a grade on.[4](https://plisio.net/ai/quillbot-ai) This source is a commercial review site rather than a peer evaluation or academic audit, so its figures should be read as one reviewer's testing, not a systematic benchmark.
On the paraphraser itself, the same reviewer reports that on documents longer than a couple thousand words the tool starts producing weird stylistic shifts mid-document, and recommends processing text in chunks.[4](https://plisio.net/ai/quillbot-ai) No independent testing of the grammar checker or summarizer appears in the available record.
## References
1. [About QuillBot - Create Great Things](https://quillbot.com/about)
2. [QuillBot - Your ideas, better writing](https://quillbot.com/)
3. [QuillBot - AI Writing Keyboard (Google Play)](https://play.google.com/store/apps/details?id=com.quillbot.mobile&hl=en)
4. [QuillBot AI Review 2026: Paraphraser, AI Detector, Pricing](https://plisio.net/ai/quillbot-ai)
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*Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Modern AI: foundation models, generative AI, and the AI industry › AI companies, people, and products › AI products and assistants › AI in devices and work software*
*Initially written Sep 17, 2026 · Edited: Oct 11, 2026; Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license