QuillBot

QuillBot is an AI writing assistant from QuillBot, the Chicago-based company now part of Course Hero. It packs eight tools into one workspace -- Paraphraser, Grammar Checker, AI Detector, Plagiarism Checker, AI Humanizer, AI Chat, Translator, and Summarizer -- and has built a strong reputation among students and professional writers since launching in 2017.

What QuillBot does:

• •Nine paraphrasing modes Standard, Fluency, Academic, Creative, Formal, Shorten, Expand, Simple, and Custom let you rewrite text while keeping intended meaning intact across academic, marketing, and business writing.
• •Grammar and style checker catch spelling, punctuation, comma splices, and tone issues in real time across web, Word, and macOS, with one-click corrections that match QuillBot's house style.
• •Plagiarism detection scan documents against billions of web sources and academic databases, with similarity scores and source links so you can rewrite or properly cite flagged passages.
• •AI Humanizer rewrite ChatGPT or Claude output to sound more natural and reduce flagging by common AI detectors, available on the Premium plan.
• •Citation generator create APA, MLA, and Chicago citations directly from a URL or DOI, useful for students filing essays or researchers preparing manuscripts.
• •Browser extension and Word add-in paraphrase and check grammar in Gmail, Google Docs, LinkedIn, and Microsoft Word without switching tabs, plus a dedicated macOS app for system-wide editing.
• •Mobile apps for iOS and Android continue editing on the go with the same modes available on desktop, including offline review of saved drafts.
• •REST API the QuillBot API lets developers integrate paraphrasing and grammar checks into their own apps, currently free during beta with rate limits.
• •Document summariser condense PDFs, articles, or research papers into bullet points or short paragraphs with adjustable length up to 6,000 words on Premium.
• •Translator across 30+ languages translate full documents while preserving formatting, with side-by-side comparison so you can verify the output reads naturally.

Pricing:

• •Free tier $0/month: 125-word paraphraser cap, 1,200-word summariser, basic grammar checker, and three writing modes. No plagiarism checker or AI Humanizer access.
• •Premium monthly $19.95/month: unlimited paraphrasing, all nine modes, plagiarism checker (25,000 words/month), AI Humanizer, faster processing, and tone analysis.
• •Premium annual $99/year ($8.33/month equivalent): same features as monthly Premium with a 58% discount, plus a 3-day money-back guarantee for new subscribers.

Limitations:

• •Free tier hits the 125-word wall fast editing a 1,500-word essay requires 12+ separate copy-paste operations and manual reassembly, making the free plan impractical for any document longer than a single paragraph.
• •Plagiarism checker is Premium-only the most-advertised feature is locked behind the $99/year plan and capped at 25,000 words/month, so heavy academic users can exhaust it within a few research papers.
• •AI Humanizer has a 25-35% false-flag rate 2026 independent tests show humanised output still trips Turnitin and GPTZero on roughly a third of passages, so it is unreliable as a guarantee against AI detection.
• •No brand-voice training unlike Grammarly Business or Jasper, QuillBot does not learn your company's preferred tone or terminology, so output still needs manual editing to match a brand voice.
• •Annual commitment for the best price the monthly plan at $19.95 is hard to justify against the $8.33/month annual rate, and there is no quarterly option to test Premium without committing for a full year.