G
GAI Detection & Humanizers toolsFull list
Check whether text reads as machine-written.
7 tools5 with a free plan6 with an API
7 tools
GG
Freemium
G
AI writing assistant for grammar, tone, rewrites and AI-text detection
Grammar & ProofreadingFree plan
G
GG
Freemium
G
AI text detector with plagiarism checks and writing replay for educators
AI Detection & HumanizersFree planAPI
O
OAI content detection, plagiarism and fact checking for publishers and educators
Free, from $12.95/mo
O
Free, from $12.95/mo
O
AI content detection, plagiarism and fact checking for publishers and educators
AI Detection & HumanizersFree planAPI
C
CDetects AI-generated text and images and checks for plagiarism
Free, from $13.99/mo
C
Free, from $13.99/mo
C
Detects AI-generated text and images and checks for plagiarism
AI Detection & HumanizersFree planAPI
R
RDeepfake detection for audio, video and images, with API and meeting protection
From $280/mo
R
From $280/mo
R
Deepfake detection for audio, video and images, with API and meeting protection
Security & FraudAPI
W
WW
From $9/mo
W
AI rewriter that restructures sentences and rewrites articles in bulk
Paraphrasing & RewritingAPI
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POnline AI paraphrasing tool with multiple rewriting modes in 20+ languages
Free, from $3.96/mo
P
Free, from $3.96/mo
P
Online AI paraphrasing tool with multiple rewriting modes in 20+ languages
Paraphrasing & RewritingFree planAPI
AI Detection & Humanizers tools compared
From each vendor's own pages, re-checked every two months. Of 6 tools we checked, 0 of 2 that state a policy don't train AI on your content, and 3 hold SOC 2 or ISO 27001.
Cost per 1,000 words processed
Cheapest paid plan divided by what it includes per month.
- 1Originality.ai$0.065
- 2WordAi$0.34
| Tool | Plagiarism checker | Writing replay | Bulk processing | Shareable reports | Docs/LMS integration |
|---|---|---|---|---|---|
| G | — | — | |||
| OOriginality.ai | |||||
| RResemble AI | — | — | — |
— means the vendor's site doesn't say.
How to choose ai detection & humanizers tools
Start with the job you need done, because this category mixes three different ones. GPTZero, Originality.ai and Copyleaks AI Detector are built to flag AI-written text, and all three also check for plagiarism. Paraphraser.io and WordAi rewrite text instead. Grammarly combines AI-text detection with grammar, tone and rewrite help, while Resemble AI targets deepfake audio, video and images rather than written text.
Next, look at the extras. GPTZero offers writing replay for educators, Originality.ai adds fact checking, and Copyleaks also detects AI-generated images.
Then compare pricing. Most tools here are freemium, with listed paid plans starting at $3.96/mo for Paraphraser.io, $12.95/mo for Originality.ai and $13.99/mo for Copyleaks. WordAi offers a free trial and starts at $9/mo, while Resemble AI is paid only, from $280/mo.
Finally, consider how you'll use it. Grammarly has the widest platform list, including desktop and mobile apps. Every tool except Grammarly lists an API, which matters if you want to build checks into your own workflow.
Frequently asked questions
Are there free AI detection tools?
Grammarly, GPTZero, Originality.ai and Copyleaks AI Detector are all listed as freemium, so each has some free access alongside paid options. Free-tier limits vary and aren't covered in our list, so check them on each tool's site. Among the rewriters, Paraphraser.io is freemium and WordAi offers a free trial.
How much do these tools cost?
Listed starting prices run from $3.96/mo for Paraphraser.io to $280/mo for Resemble AI. In between are WordAi at $9/mo, Originality.ai at $12.95/mo and Copyleaks AI Detector at $13.99/mo. Grammarly and GPTZero are freemium, but we don't have a listed starting price for their paid plans.
What should I look for in an AI detector?
First, make sure it checks the right kind of content. GPTZero and Originality.ai focus on text, Copyleaks AI Detector covers text and images, and Resemble AI covers deepfake audio, video and images. Then consider extras such as plagiarism checks, writing replay or fact checking, along with API access and browser extensions. We did not test these tools, so we can't say which is most accurate. Try your own samples before relying on the results.
What are the alternatives to GPTZero?
Originality.ai and Copyleaks AI Detector are the closest alternatives on our list. Both detect AI text, check for plagiarism and offer an API. Originality.ai adds fact checking, and Copyleaks also detects AI-generated images. Grammarly is another option if you also want grammar, tone and rewrite help in one tool.