In 2025, the line between human and machine-generated text is blurrier than ever, and an AI text detector can be required to tell if text is written by a human or an AI. With the sophistication of models like GPT-4 and beyond, identifying AI-written content has become a critical need for educators, publishers, SEO specialists, and businesses. An AI writing detector is a specialized tool designed to analyze a piece of writing and determine the probability of it being generated by an artificial intelligence model. These tools scrutinize patterns, word choices, sentence structures, and other linguistic markers to flag synthetic content. This guide explores the 20 best AI text detector tools available today, helping you maintain authenticity and academic integrity in a world saturated with AI.
1. Originality.ai
Originality.ai is a top-tier choice for serious content publishers, SEO agencies, and website owners who need high accuracy. Its features include a robust plagiarism checker integrated alongside its AI detection capabilities, team management functions, and full site scanning via API. Pricing is credit-based, typically starting around $0.01 per 100 words, making it a scalable solution for high-volume users. This AI writing detector is ideal for use cases like verifying freelance writer submissions, auditing website content for Google’s helpful content guidelines, and ensuring a portfolio of websites remains free of AI-generated text.
2. Copyleaks
Copyleaks provides a comprehensive suite of tools that includes a highly reliable AI content detector, a multi-language plagiarism checker, and LMS integration capabilities. A standout feature is its ability to detect source code plagiarism and AI-generated code. Pricing is offered through monthly subscriptions catering to both individuals and businesses, with a limited free version available. As a highly versatile AI text detector, it’s used extensively in educational institutions to check student assignments, by law firms to verify document originality, and by businesses to ensure marketing copy is authentic.
3. GPTZero
Originally created as a university project, GPTZero has evolved into one of the most popular tools, particularly within academia. It provides a clear, color-coded highlighting of sentences likely written by AI and gives an overall probability score. Its pricing model is freemium, offering a certain number of free checks before requiring a subscription for higher volume use. The primary use case for this effective AI text detector is for teachers, professors, and academic institutions to quickly and easily check student essays and reports for AI assistance.
4. Writer.com AI Content Detector
The AI content detector from Writer.com is a free and straightforward tool designed for quick analyses. Users can simply paste text (up to 1,500 characters) and receive an instant “detection score” indicating the percentage of human-written content. There is no cost to use this specific tool, although it is part of a larger suite of paid enterprise writing tools. This AI text detector is perfect for content creators, marketers, and editors who need a fast, on-the-spot check of a short piece of text, like a product description, social media post, or a single paragraph.
5. Turnitin
Turnitin is the gold standard for academic integrity, long known for its plagiarism detection and now featuring advanced AI writing detection integrated into its feedback studio. Its technology is built to distinguish between AI and human writing within student submissions seamlessly. Pricing is enterprise-level, sold directly to educational institutions, so individual users cannot purchase it. The use case for this AI text detector is exclusively for schools, colleges, and universities to uphold academic honesty policies and provide feedback on student originality.
6. Winston AI
Winston AI markets itself as a highly accurate tool with a low rate of false positives, claiming a 99.6% accuracy rate in detecting AI-generated content. It features a clean interface, printable reports, and project management capabilities. The pricing structure is a freemium model with a free trial and then tiered monthly subscriptions based on the number of words scanned. This AI text detector is built for web publishers, educators, and writers who require a high degree of confidence in their results when checking articles, academic papers, and other important documents.
7. Scribbr
Powered by Turnitin’s technology, Scribbr’s AI Detector is designed specifically for students. It’s part of a broader suite of academic tools including a plagiarism checker, citation generator, and proofreading services. The pricing is usually bundled with their other services or available through limited free use, with paid options for more extensive checks. This AI text detector is ideal for students who want to self-check their work to ensure it’s original and properly cited before submitting it to their university’s official checking software.
8. Crossplag
Crossplag offers an integrated solution that checks for both plagiarism and AI-generated content in a single scan. It supports multiple languages and provides a side-by-side comparison for easy analysis. Pricing is available for individuals, institutions, and businesses, often on a credit-based system. The primary use case for this AI text detector is for users who need an efficient, two-in-one tool, making it popular in academic environments and among content agencies managing multiple writers and sources.
9. Content at Scale AI Detector
Content at Scale offers an AI writing platform, and its free AI detector is a core part of its ecosystem. It is designed to analyze text for predictability, patterns, and phrasing common in AI writing. The tool is free to use by simply pasting text into the web interface. While it promotes their AI writing service, this AI text detector is a valuable standalone tool for SEOs and content marketers to quickly assess if a piece of content might be flagged by search engine algorithms as unhelpful or spammy.
10. Sapling AI Detector
Sapling offers an AI detector as part of its larger suite of business-focused communication tools, which include grammar checking and autocompletion for customer service teams. A key feature is its browser extension and API, allowing for integration into existing workflows. The detector is free for short texts, with API access being a paid feature. This AI text detector is best suited for businesses, especially in customer support and sales, to monitor team messages and ensure that AI-assisted communication remains authentic and on-brand.
11. ZeroGPT
ZeroGPT is one of the most widely used free tools due to its simplicity and accessibility. It provides a percentage score indicating the likelihood of AI involvement by analyzing text for perplexity and burstiness. The service is free and ad-supported, with usage limits for very long texts. Because of its ease of use and no-cost model, this AI text detector is a go-to option for students, casual bloggers, and anyone needing a quick, no-frills analysis of a document.
12. Undetectable.ai
Undetectable.ai offers a unique dual function: it acts as both an AI text detector and an AI “humanizer.” It first scans text to detect AI and then provides tools to rewrite it to appear more human. Pricing is based on monthly subscriptions with varying word counts. The primary use case for this AI text detector is for users who not only want to identify AI content but also need to revise it to bypass other detectors, making it popular among marketers and content creators looking to leverage AI for brainstorming while retaining a human touch.
13. GLTR
GLTR, which stands for Giant Language Model Test Room, is a more technical tool developed by the MIT-IBM Watson AI Lab. Instead of giving a simple probability score, it visualizes the likelihood of each word being chosen by an AI model, color-coding the text. It is a free, browser-based tool. This AI text detector is best for researchers, developers, and tech-savvy users who want a deeper, more forensic analysis of how a text was constructed, rather than a simple “AI or not” verdict.
14. Kazan SEO
Kazan SEO provides a free AI content detector specifically tailored to the needs of SEO professionals. It’s designed to help webmasters avoid penalties from search engines by identifying content that might not meet helpfulness standards. The tool is free to use directly on their website. The main use case for this AI text detector is for SEO specialists and website owners to audit their own or competitors’ content to ensure it aligns with search engine quality guidelines.
15. Corrector App AI Content Detector
Corrector App offers a suite of writing tools, including a grammar checker and a free AI content detector. A key strength is its support for multiple languages, allowing users to check text in English, Spanish, French, Portuguese, and Italian. The tool is free for general use. This makes it an excellent AI text detector for international students, translators, and global marketing teams who work with content in various languages.
16. AI-Proctor
AI-Proctor offers a comprehensive suite of tools for remote examination and assessment, which includes an AI text detector as a key feature. It’s designed to ensure academic integrity during online tests by flagging suspicious writing patterns. Pricing is enterprise-level and sold to educational and certification institutions. The primary use case for this AI text detector is in the context of proctored online exams, where it helps invigilators ensure that essay answers are not being generated by AI in real-time.
17. Plagibot
Plagibot is a straightforward tool that primarily functions as a plagiarism checker but has incorporated AI detection to meet modern needs. It offers a free tier with limited checks and a premium subscription for more comprehensive scanning. This AI text detector is suitable for students and bloggers who need a simple, affordable tool to check for both copy-paste plagiarism and AI generation in their work before publishing or submission.
18. Hugging Face AI Detector
Hugging Face, a major hub for the AI community, hosts various open-source AI content detection models. These are typically free to use on their platform but are more technical in nature, often based on the output of models like RoBERTa. Pricing is not applicable as they are community-developed tools. This type of AI text detector is ideal for developers, researchers, and hobbyists who want to experiment with different detection models or integrate AI detection capabilities into their own applications.
19. Writefull’s GPT Detector
Writefull provides a suite of AI-based tools to help with academic writing, and its GPT Detector is a part of this offering. It is specifically trained on academic texts, potentially making it more attuned to the nuances of scholarly writing. The detector is available for free with registration. This AI text detector is an excellent choice for researchers, PhD students, and academics who want to check their manuscripts, literature reviews, and other scholarly documents.
20. CheckforAI
CheckforAI offers a clean, minimalist interface for quickly checking text. It focuses on providing a clear and easy-to-understand result, often categorizing content as “Human,” “AI,” or “Likely AI.” The service operates on a freemium model, providing a few free scans before requiring a paid plan for continued use. This AI text detector is designed for general-purpose use, making it a great option for freelance writers, HR professionals screening cover letters, or anyone needing an intuitive and fast tool to verify the authenticity of a document.
Conclusion: AI Text Detectors Are Now Vital
Choosing the right AI text detector in 2025 is less about finding a single perfect tool and more about selecting the one that aligns with your specific needs. The landscape is diverse and specialized: educators may gravitate towards Turnitin or GPTZero for upholding academic integrity, while SEO professionals and publishers will find immense value in the detailed, high-stakes analysis provided by Originality.ai. For quick, free checks, tools like ZeroGPT and Writer.com offer incredible accessibility to everyone.
The relationship between AI content generation and detection is a dynamic one—a constant technological race where each side pushes the other to become more sophisticated. As AI models evolve to write with greater nuance, the technology behind every AI text detector on this list will undoubtedly advance alongside them. Ultimately, integrating one of these tools into your workflow is no longer a niche requirement but a fundamental practice for anyone who creates, evaluates, or consumes digital content. By doing so, you can protect your academic integrity, enhance your content strategy, and confidently navigate a future where verifying authenticity is more important than ever.