Copyleaks vs GPTZero

Updated November 2026 · AppBreakup editorial

Copyleaks

AI content detector and plagiarism checker for text, code, images and video, with a developer API.

Free plan + paid

Visit Copyleaks Copyleaks profile

GPTZero

AI detector that estimates how much of a text was written by ChatGPT, Claude or Gemini.

Free plan + paid

Visit GPTZero GPTZero profile

The short answer

Copyleaks and GPTZero both flag AI-written text, but Copyleaks is the broader service: it pairs plagiarism and AI detection and also checks source code, images, video and citations, with an API and SDKs for six languages. GPTZero focuses on classrooms, with Google Docs, Classroom and Canvas integrations and Writing Replay. Publishers and developers will lean to Copyleaks; teachers to GPTZero.

Copyleaks or GPTZero: our take

Both tools highlight the passages that look machine-written, and both produce probabilities rather than proof, so either can mislabel human writing. The difference is scope. Copyleaks compares text against the web and private repositories and runs plagiarism and AI detection in a single scan. It has added detection of AI-generated images and video, source-code plagiarism checks, a grammar checker, text moderation and a citation checker that flags fabricated references. GPTZero began in January 2023 as an AI detector for teachers and has added a plagiarism checker, a grammar and feedback tool, and Writing Replay, which shows how a Google Doc was typed over time as evidence of authorship.

GPTZero fits more naturally into a classroom. It integrates with Google Docs, Google Classroom, Canvas and Zapier, has a Chrome extension, and checks texts under 10,000 characters without an account. It fully supports English, German, Portuguese, French and Spanish. Copyleaks also serves schools through learning-platform integrations, but its strengths show more for publishers, companies governing AI use, and developers: its REST API has official SDKs for Python, JavaScript, Java, C#, PHP and Ruby, and it can compare against private document databases. GPTZero offers a developer API as well.

Both are freemium. Copyleaks charges credits by pages scanned, with a small free allowance, which can add up for long documents. GPTZero needs a free account or paid plan for longer scans and the extra tools, and teams can buy shared word allowances.

Pick GPTZero for a teacher-friendly check inside Google Docs or Canvas, with typing history as evidence. Pick Copyleaks for one service covering plagiarism, AI text, code and images, or for building detection into a product through an API.

Choose Copyleaks if…

Schools, publishers and developers who need AI detection and plagiarism checks in one service or API
Combines plagiarism and AI detection in a single scan
Covers source code, images and video, not just prose

Choose GPTZero if…

Teachers and schools that want an AI check built into Google Docs, Classroom and Canvas
Short texts can be checked without signing up
Writing Replay shows how a document was actually typed

What is Copyleaks?

Copyleaks checks whether content is original and whether it was written or generated by AI. Its core products are a plagiarism checker that compares text against the web and private repositories, and an AI text detector that highlights the phrases that look machine-written. It has since added detection of AI-generated images and video, plagiarism checks for source code, a grammar checker, a citation checker that flags fabricated references, and text moderation. Schools and universities use it for academic integrity, often through integrations with learning platforms, while publishers and companies use it before publishing or to govern AI use. Individuals can work in the web app or browser extension, and developers get a REST API with official SDKs for six languages. Pricing is credit-based by pages scanned, with a small free allowance for trying the detector and paid plans for individuals and organisations.

What is GPTZero?

GPTZero checks a piece of writing and estimates how likely it is to be AI-generated, highlighting the sentences that look machine-written. It started in early 2023 as a tool for teachers worried about ChatGPT essays and is still aimed mostly at education, with integrations for Google Docs, Google Classroom and Canvas plus a Chrome extension. Around the core detector it has added a plagiarism checker, a grammar and feedback tool, and Writing Replay, which shows how a Google Doc was typed over time as evidence of authorship. You can paste short texts without an account; longer scans and the extra tools need a free account or a paid plan, and teams can buy shared word allowances. A developer API lets schools and platforms build detection into their own products. Like every AI detector, its scores are probabilities rather than proof, so results are best used as a prompt for a conversation rather than as a verdict.

Side by side

Attribute	Copyleaks	GPTZero
Pricing	Free plan + paid	Free plan + paid
Open source	No	No
Self-hostable	No	No
Platforms	Web, Browser extension	Web, Browser extension
Best for	Schools, publishers and developers who need AI detection and plagiarism checks in one service or API	Teachers and schools that want an AI check built into Google Docs, Classroom and Canvas
Status	Active	Active