| Undetectable AI | GPTinf | |
|---|---|---|
| Starting price | $9.99/mo | $12/mo |
| Free tier | 250 words | 200 words |
| Bundled detector | Yes | No |
| Founded | 2022 | 2023 |
| Best for | Teams that want one tool to both check and rewrite content across multiple AI models. | Writers who want granular control over tone and which specific sentences get rewritten. |
Price: Undetectable AI is cheaper to start, at $9.99/mo vs $12/mo.
Undetectable AI: $9.99/mo for the entry tier; higher tiers scale by word volume.
GPTinf: From $12/mo, scaling with monthly word volume.
Free tier: Undetectable AI offers a more generous free tier (250 words).
If you just want to test either tool before paying, Undetectable AI's 250-word allowance gives you more room to evaluate quality.
Detection performance
Undetectable AI: Frequently cited as a top-tier performer against GPTZero and Originality.ai, though results vary by source text length and topic.
GPTinf: Marketed as being trained directly against detector models rather than general paraphrasing, which independent testers cite as the reason its scores hold up on technical text.
AI detector included: Undetectable AI bundles a built-in detector; GPTinf does not.
Strengths at a glance
Undetectable AI
- Runs output against multiple detector models before returning it
- Supports long-document processing without manual chunking
- Adjustable readability and purpose settings (story, essay, article, email)
GPTinf
- Eight distinct rewriting modes (Academic, Formal, Informal, Creative, Simple, Standard, Expand, Shorten)
- Freeze-keyword feature protects technical terms and proper nouns from being altered
- Selective, sentence-level rephrase instead of forcing a full rewrite
Our verdict
Choose Undetectable AI if: teams that want one tool to both check and rewrite content across multiple ai models. Choose GPTinf if: writers who want granular control over tone and which specific sentences get rewritten.