QuillBot vs Undetectable AI

QuillBot

QuillBot remains the fastest way to reword a paragraph you have already written, and the free tier is enough for occasional use; Premium at roughly $8 to $20 a month depending on term buys the extra modes, longer inputs and the plagiarism checker that students actually want. Against a general chatbot it wins on speed and a purpose-built interface, not on writing quality, and against Grammarly it is cheaper but narrower.

Pros

• +Free tier includes grammar checking, two paraphrase modes, translation and AI detection
• +Extensions and apps for Chrome, Windows, macOS, Safari, iOS and Android keep it inside the writing surface
• +Paraphrase modes and a synonym slider give more control than a one-shot rewrite prompt
• +Backed by Learneo, a large education group, rather than an anonymous operator

Cons

• −Month-to-month Premium is about 2.4 times the annual rate, so the headline low price assumes a year up front
• −The site blocks automated access, so none of the figures here come from its own pricing page
• −The App Store listing itself disagrees on how many Premium paraphrase modes exist (8 versus 10+)
• −The heavy student use and the AI detector attract academic-integrity scrutiny that can rebound on users

Undetectable AI

Buy it only if you accept that passing a detector is a moving target: detector vendors retrain constantly, and text that cleared last month can flag next month. As a multi-format detection dashboard it is more defensible than as a bypass tool.

Pros

• +Detector and rewriter run in one pass, so you see which sentences changed and why
• +Coverage extends past text into image, voice, video and document classifiers
• +Browser extension works inside Docs and Gmail rather than a separate tab
• +Entry tier is genuinely cheap at annual rates

Cons

• −Rewrites often flatten voice and add filler to break statistical patterns
• −Detection on short passages is unreliable in both directions
• −Word quotas drain fast because rejected attempts still consume them
• −The free trial caps at 250 words, barely enough to judge output quality

Is QuillBot cheaper than Undetectable AI?

On published entry prices, Undetectable AI starts lower — $9.99/mo against $19.99/mo for QuillBot. Entry price is the lowest paid plan as we last verified it; what each plan includes differs.

Does QuillBot or Undetectable AI have a free tier?

Both: QuillBot has a free tier, and Undetectable AI has a free tier.

Which has a public API, QuillBot or Undetectable AI?

Undetectable AI ships a public API, as of our last verification. A public API for QuillBot is not confirmed by us — check its developer docs before you plan an integration.