kitio.aiGPTZero vs Isgen
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. GPTZero starts at See pricing page and Isgen starts at See pricing page. Check both pricing pages for current plans.
At a glance
Best for
Pricing model
Starting price
Free plan
Made by
Based in
Rating
Key features
- AI probability score
- Sentence highlighting
- Writing replay in Google Docs
- Plagiarism checker
- API
- Sentence-level AI detection
- Plagiarism checker
- Bulk file scanning
- Grammar checker
- AI humanizer
- Presentation maker
| Feature | GPTZero | Isgen |
|---|---|---|
| Best for | AI detector that flags machine-written text for teachers and editors | AI detector with plagiarism checking, humanizer and slide maker |
| Category | Writing | Writing |
| Pricing model | Freemium | Freemium |
| Starting price | See pricing page | See pricing page |
| Free plan | Yes | Yes |
| Made by | GPTZero | Isgen |
| Based in | United States | – |
| Rating | No ratings yet | No ratings yet |
| Key features |
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Both offer: Plagiarism checker.
Pricing compared
GPTZero starts at See pricing page and Isgen starts at See pricing page. Check both pricing pages for current plans.
Free plan
Cheapest paid plan
Top plan
Free trial
4 plans
Free
Free
- Up to 5,000 characters per check
- Basic AI detection
Academic
$8/mo billed yearly
- 350,000 detection words a month
- Premium plagiarism checker
- Batch file upload
Writing
$15/mo billed yearly
- 50,000 humanizer words a month
- AI proofreader
- 4,000 presentation credits
Ultimate
$24/mo billed yearly
- Unlimited words
- Humanizer and proofreader
- 8,000 presentation credits
- Priority support
Prices in USD, checked Oct 28, 2026 or later. Plans change often, so confirm on each tool's site before you buy.
Pros and cons
GPTZero
- Free tier for regular checks
- Writing replay shows the drafting process
- LMS integrations
- Scores are probabilities, not proof
- Can misjudge non-native English writing
Isgen
- Highlights AI text sentence by sentence
- Bulk scanning on paid plans
- Bundles plagiarism and grammar checks
- AI detectors can flag human writing
- Free checks capped at 5,000 characters
- Listed prices assume yearly billing
Which one should you choose?
Choose GPTZero if you want:
- Free tier for regular checks
- Writing replay shows the drafting process
- LMS integrations
Watch out: scores are probabilities, not proof.
Choose Isgen if you want:
- Highlights AI text sentence by sentence
- Bulk scanning on paid plans
- Bundles plagiarism and grammar checks
Watch out: ai detectors can flag human writing.
GPTZero vs Isgen FAQ
What is the difference between GPTZero and Isgen?
GPTZero: AI detector that flags machine-written text for teachers and editors. Isgen: AI detector with plagiarism checking, humanizer and slide maker. Both are writing tools.
Is GPTZero or Isgen cheaper?
GPTZero starts at See pricing page and Isgen starts at See pricing page. Check both pricing pages for current plans.
Do GPTZero and Isgen have free plans?
GPTZero: Yes. Isgen: Yes.
Who makes GPTZero?
GPTZero is made by GPTZero, based in United States.
Who makes Isgen?
Isgen is made by Isgen.
Which should I choose, GPTZero or Isgen?
Choose GPTZero if you value free tier for regular checks and writing replay shows the drafting process. Choose Isgen if you value highlights ai text sentence by sentence and bulk scanning on paid plans.