Check-Plagiarism vs Copyleaks AI Detector

Check-Plagiarism is a plagiarism-checking service for students, teachers, researchers, content creators, and digital publishers. It accepts pasted or typed text and DOC, DOCX, TXT, or PDF uploads, with a listed maximum of 7,000 words per document. The checker reports duplicated passages, sentence-level matches, similarity percentages, and matching sources. Its AI is described as detecting paraphrased or lightly edited text as well as exact matches. The service says it checks billions of web pages and provides access to academic databases and publications, with support claimed for more than 20 languages. Reports can be downloaded or shared, including as PDF. Free online use is available with limited searches; registered accounts can increase the limit. Plans include Monthly at $14.99 a month and Annual at $8.33 a month, billed $99.99 every 12 months. API access and LMS integrations are listed.

Copyleaks AI Detector identifies AI-written text, including writing that mixes AI and human passages. It supports more than 30 languages and names GPT-5, GPT-4, ChatGPT, Claude, Gemini, DeepSeek, Llama, Bloom, Rytr, and Jasper among the sources it detects. AI Logic explains flagged results, displays AI phrase frequency, and can identify text appearing in published content elsewhere. The web detector scans up to 25,000 characters without login; the website platform requires at least 255 characters and accepts up to 2,000 pages. A Chrome and Edge extension accepts 350 to 25,000 characters, and a Google Docs add-on and education LMS integrations connect it to other workflows. Personal costs $13.99 a year with annual billing or $16.99 a month; Pro costs $74.99 a year with annual billing or $99.99 a month. A free plan and free trial are listed. Copyleaks says data is encrypted at rest with AES-256, reports SOC 2 and SOC 3 certifications, and supports GDPR compliance.