Shortlist by what you need
Start here if you know why you are leaving GPTZero.
Want the closest match?
Winston AIMost similar to GPTZero in what it does, its category and its price.
Visit (opens Winston AI in a new tab)Need a free plan?
GrammarlyHas a free plan, rated 4.6 out of 5.
Visit (opens Grammarly in a new tab)Want to pay less than GPTZero?
CopyleaksFrom $9.99/mo, against from $15/mo for GPTZero.
Visit (opens Copyleaks in a new tab)Want the best rated?
Originality.AIRated 4.5 out of 5 in our review, against 4.4 for GPTZero.
Visit (opens Originality.AI in a new tab)
At a glance
Green means better than GPTZero, red means worse. Prices are starting prices per month.
| Tool | Our rating | Starts at | Free plan | Best for | Compare |
|---|---|---|---|---|---|
 GPTZeroBaseline | 4.4 | $15/mo | Yes | An AI detector built at Princeton that identifies LLM-generated text and now backs Superhuman's authenticity tools | |
| Winston AI | 3.5−0.9 | Free | Yes | AI content and image detection claimed accurate 99.98% of the time - sentence-level highlights, plagiarism checks, and deepfake detection in one report. | vs GPTZero |
| Copyleaks | 4.2−0.2 | $9.99/mo$5.01 less | Yes | Copyleaks scans text and images for plagiarism and AI-generated content across dozens of languages for schools and businesses. | vs GPTZero |
| Originality.AI | 4.5+0.1 | $12.95/mo$2.05 less | Yes | An AI and plagiarism detector built for publishers who need to verify content before it goes live | vs GPTZero |
 Undetectable AI | 3.2−1.2 | Free | Yes | Detects AI content across text, image, audio and video, and also rewrites text to evade detection. | vs GPTZero |
 StealthWriter | 2.9−1.5 | $20/mo$5 more | Yes | Rewrites AI-generated text to defeat AI detectors, and ships a detector to check the result. | vs GPTZero |
 WriterBuddy | 3.7−0.7 | Free | Yes | 40+ academic writing tools in one place - co-writer, plagiarism checker, citation generator (MLA/APA/Chicago), ChatPDF - across 25+ languages. | vs GPTZero |
| Grammarly | 4.6+0.2 | $12/mo$3 less | Yes | The writing assistant almost everyone has already used | vs GPTZero |
 Dechecker | 3.7−0.7 | Free | Yes | Sentence-level AI detection across ChatGPT, Claude and Gemini output, paired with one-click humanization rewrites. | vs GPTZero |
The alternatives in detail
In order of how closely each one matches GPTZero.
Winston AI
3.5Free
vs GPTZero−0.9
AI content and image detection claimed accurate 99.98% of the time - sentence-level highlights, plagiarism checks, and deepfake detection in one report.
- AI text detection claimed 99.98% accurate across major LLMs
- AI-generated image and deepfake detection
- Plagiarism checking alongside AI detection
Free tier available with no credit card required
Paid tier pricing isn't shown on the homepage
Copyleaks
4.2$9.99/mo
vs GPTZero$5.01 less−0.2
Copyleaks scans text and images for plagiarism and AI-generated content across dozens of languages for schools and businesses.
- Combined plagiarism and AI-content detection in one scan
- Multi-language support across dozens of languages
- Image-based AI detection alongside text scanning
Combines plagiarism and AI-detection in one subscription instead of two tools
Credit-based pricing gets confusing to estimate for high-volume users
Originality.AI
4.5$12.95/mo
vs GPTZero$2.05 less+0.1
An AI and plagiarism detector built for publishers who need to verify content before it goes live.
- AI content detection independently benchmarked for accuracy against competing detectors
- Live-web plagiarism checking rather than a static, outdated reference database
- Bundled fact-checking, grammar review, and readability scoring in the same platform
Accuracy claims are independently benchmarked rather than only self-reported
No unlimited free tier; the free AI checker is capped at a small word count
Undetectable AI
3.2Free
vs GPTZero−1.2
Detects AI content across text, image, audio and video, and also rewrites text to evade detection.
- AI text detection with flagged sections
- Image, audio and video AI detection
- Fake PDF detector
Detection across image, audio and video, not just text
Ships a humanizer for evading detection, with students among named users
StealthWriter
2.9$20/mo
vs GPTZero$5 more−1.5
Rewrites AI-generated text to defeat AI detectors, and ships a detector to check the result.
- AI humanizer with light, medium and aggressive modes
- Bundled AI detector to verify the output
- Deep Scan sentence-by-sentence analysis
Sentence-level control rather than one blanket rewrite
Its purpose is defeating detection, and students are the first audience named
WriterBuddy
3.7Free
vs GPTZero−0.7
40+ academic writing tools in one place - co-writer, plagiarism checker, citation generator (MLA/APA/Chicago), ChatPDF - across 25+ languages.
- Co-Writer: brainstorming, autocomplete, grammar checking
- Citation generator: MLA, APA, Chicago formats
- Plagiarism checker and AI content detector
Covers the full academic writing workflow, not just drafting
40+ tools means real exploration to find the right one for a task
Grammarly
4.6$12/mo
vs GPTZero$3 less+0.2
The writing assistant almost everyone has already used.
- Real-time grammar, spelling, and punctuation checks
- Tone detection and clarity rewrite suggestions
- GrammarlyGO generative drafting and rewriting
Free tier is genuinely useful long-term, not just a trial
Generative features feel bolted onto an older core product
Dechecker
3.7Free
vs GPTZero−0.7
Sentence-level AI detection across ChatGPT, Claude and Gemini output, paired with one-click humanization rewrites.
- Sentence-level AI detection across ChatGPT, Claude and Gemini output
- One-click humanization rewrite suggestions
- Bulk file upload and batch analysis
Sentence-level flagging is more actionable than one whole-document score
AI detectors carry real false-positive/false-negative rates industry-wide
FAQ
Questions people ask
Is GPTZero free?
GPTZero has a free plan, and paid plans start from $15/mo.
What is the best free alternative to GPTZero?
Grammarly is the highest-rated alternative here with a free plan (4.6 out of 5). Other free options: Originality.AI, Copyleaks, WriterBuddy.
What is the cheapest alternative to GPTZero?
Among paid plans, Copyleaks has the lowest starting price (from $9.99/mo). If you need it free, start with Grammarly.
How did you pick these alternatives?
We match tools on what they do, their category and their price, using the details in our directory. Ratings come from our reviews and reader reviews.