IsItAI vs QuillBot AI Detector: AI detector comparison
A side by side look at pricing, methodology, language support and best-fit use case. Every claim on this page is linked to a source at the bottom.
Last updated . Reviewed by IsItAI Editorial.
At a glance
IsItAI
UK, 2024UK-built AI detection that gives you a confidence score, not a verdict.
- Pricing
- From £4.99/month
- Free tier
- 5 scans/day free
- API
- Yes
- Languages
- 30
QuillBot AI Detector
US, 2017 (AI detector 2023)Free detector from the company best known for paraphrasing tools.
- Pricing
- Free (Premium suite from $9.95/month)
- Free tier
- Free unlimited
- API
- No
- Languages
- 3
Side by side
| Feature | IsItAI | QuillBot AI Detector |
|---|---|---|
| Free tier | 5 scans/day free | Free unlimited |
| Starting price | From £4.99/month | Free (Premium suite from $9.95/month) |
| Cost per 1k words | £0.05 (Pro plan equivalent) | Free |
| API available | Yes | No |
| Languages supported | 30 | 3 |
| Founded | 2024 | 2017 (AI detector 2023) |
| Country | UK | US |
| Primary audience | Educators, recruiters and content teams | Students and casual writers |
| Best for | Teachers, students and recruiters who want a clear confidence score and source-passage highlighting | Quick free checks alongside QuillBot's paraphraser |
| Known weakness | Smaller brand than US incumbents | Conflict of interest. The same company sells the paraphraser that defeats detectors |
How each tool works
IsItAI
Method: Multi-model ensemble. Combines several open detectors and weights agreement. Returns a confidence band rather than a binary verdict.
Data handling: GDPR compliant. UK and EU hosted. Submitted text is not stored after the scan completes.
QuillBot AI Detector
Method: Free classifier within the QuillBot writing suite.
Data handling: Stores submissions for product improvement.
How accurate are AI detectors? What the research says
Two findings from independent academic research apply to almost every detector on this list, including IsItAI and QuillBot AI Detector.
1. False positives on non-native English writers. Liang et al. (Stanford, 2023) found that GPT detectors flagged over half of TOEFL essays written by non-native English speakers as AI-generated, while flagging almost none of the essays from US students. If your use case involves non-native English writers, never treat a detector verdict as proof on its own.
2. Paraphrasing reliably defeats classifiers. Sadasivan et al. (Maryland, 2023) showed that running AI output through a paraphraser drops detection performance close to chance. Both IsItAI and QuillBot AI Detector are vulnerable to this.
Where IsItAI wins
- API access available. QuillBot AI Detector is web only.
- Wider language support at 30 versus 3 languages.
- Built for educators, recruiters and content teams.
Where QuillBot AI Detector wins
- Built for students and casual writers.
- Method: Free classifier within the QuillBot writing suite.
Which one should you pick, IsItAI or QuillBot AI Detector?
IsItAI suits teachers, students and recruiters who want a clear confidence score and source-passage highlighting. QuillBot AI Detector suits quick free checks alongside quillbot's paraphraser. Pick based on which fits your workflow. Treat any detector verdict as a screening signal, not proof.
Frequently asked questions
Is IsItAI free?
5 scans/day free
Is QuillBot AI Detector free?
Free unlimited
Can either tool be fooled by paraphrasing?
Yes. Sadasivan et al. (2023) demonstrated that paraphrasing reliably defeats most AI classifiers. Treat any detector verdict as a screening signal, not proof.
Are AI detectors fair to non-native English writers?
Independent research (Liang et al. 2023) found high false-positive rates for non-native English writing. Always combine a detector signal with other evidence, never use it as a sole basis for an academic or hiring decision.
Which one should I pick if I have to choose one, IsItAI or QuillBot AI Detector?
IsItAI suits teachers, students and recruiters who want a clear confidence score and source-passage highlighting. QuillBot AI Detector suits quick free checks alongside quillbot's paraphraser. Pick based on which fits your workflow. Treat any detector verdict as a screening signal, not proof.
Try IsItAI free
5 free scans a day. No credit card. UK hosted and GDPR compliant.
Sources and further reading
- IsItAI homepage
- Pricing
- How it works
- QuillBot AI detector
- Sadasivan et al. (2023): Can AI-generated text be reliably detected?
- Liang et al. (Stanford, 2023): GPT detectors are biased against non-native English writers