Best Plagiarism Checker Software

Copyscape is a long running plagiarism and duplicate content detection service built for website owners, writers, editors, and digital marketers who want to confirm their content is not copied elsewhere online. The free tier runs a basic search using search engine indexes, while Copyscape Premium adds copy and paste checking, PDF and Word uploads, batch searches of up to 10,000 pages, a Private Index for comparing against unpublished content, and an API returning results in JSON, XML, or HTML.

Premium is billed pay per search rather than as a flat subscription, costing 3 cents per search of up to 200 words plus 1 cent per additional 100 words. A separate product, Copysentry, continuously monitors the web for copies of a site's pages and emails alerts, with Standard and Professional tiers priced monthly per 10 pages monitored.

DupliChecker is a web based plagiarism checker that scans up to 25,000 words per search using AI based technology and partial match detection at the paragraph level, so it can catch reworded or restructured copying rather than only exact matches. It accepts copy and paste, URL, and file upload input across formats including doc, docx, odt, pdf, rtf, and txt, and can import files directly from Google Drive and Dropbox. A free AI content detector, grammar checker, and paraphrasing tool are bundled alongside the core checker.

A limited free version is available without signup, while paid access is sold in weekly, monthly, and yearly tiers offering larger word counts and search quotas, plus a Plagiarism API for integrating real time checks into other websites.

Plagiarism Checker X is Windows based plagiarism detection software that pairs a downloadable desktop application with online deep search across more than 16 billion web pages, documents, and blogs. It includes an AI generated content detector, side by side document comparison, a bulk search mode for scanning batches of assignments, and a readability checker covering metrics like Flesch and Gunning Fog scores. Bibliography and quote exclusion features make it useful for academic work.

The software is sold as a one time perpetual license rather than a subscription. A free Basic version allows 30 searches per day with limited word counts, a Professional single user license costs $39.95, and a Business license covering five users costs $147.95. Files stay on the user's device during analysis rather than being stored in an online database.

Turnitin is an academic integrity platform used by schools, colleges, and universities to detect plagiarism and flag AI-generated writing in student submissions. Its core Similarity product compares submitted work against a large database of web content, academic publications, and previously submitted papers, while its AI writing detection feature estimates the likelihood that text was produced by generative AI. Feedback Studio adds grading, rubrics, and peer review tools for classroom use, and iThenticate serves researchers and publishers checking manuscripts before submission.

Turnitin is sold through custom institutional licenses rather than public self-serve plans, with cost depending on institution size, selected modules, and deployment scope. It integrates with learning management systems such as Canvas, Blackboard, and Moodle via LTI. There is no direct individual purchase option for classroom use; iThenticate is the individual-friendly product for researchers and authors.

Copyleaks is an AI-powered plagiarism and AI-generated content detection platform used by educators, publishers, and businesses. Its plagiarism checker compares submitted text against web content, academic sources, and internal repositories across more than 100 languages, while its AI detector analyzes text at the sentence, paragraph, and document level to estimate the probability that content was AI-generated. A companion tool, Codeleaks, checks source code for plagiarism.

Copyleaks offers a limited free tier plus paid personal and business plans billed on a monthly credit system, with each credit covering roughly 250 words or one image. Enterprise and education customers receive custom quotes based on volume and integration needs. The platform provides an API and LMS integrations, and annual billing offers a discount over monthly pricing.

Grammarly's plagiarism checker is a feature within the broader Grammarly writing assistant rather than a standalone product. It scans documents against billions of web pages and ProQuest's academic databases, then returns a plagiarism score along with a list of matching sources. The feature works alongside Grammarly's grammar, style, and AI writing suggestions inside its browser extension, desktop app, and web editor.

Plagiarism checking is available only on Grammarly's paid Pro and Business plans; it is not included in the free tier. Pro is billed monthly or at a lower effective rate with annual billing, while Business plans are billed per seat annually and add team management and analytics. Grammarly does not offer a separate discounted plan specifically for a standalone plagiarism checker.

Quetext is a plagiarism and AI content detection platform built around its proprietary DeepSearch technology and ColorGrade originality interface, which highlight matched passages and flag likely paraphrased content. It targets students, teachers, writers, and professionals who need to verify originality before submitting or publishing text. Beyond detection, Quetext includes an AI writing tutor called AITutorMe, a citation generator, and grammar and spell check tools.

Quetext offers a free plan with a 1,000-word limit for both plagiarism and AI checks, along with paid Essential, plagiarism-only, and AI-detector-only individual plans billed monthly with annual discounts. Bundle tiers and a usage-based Professional plan serve teams and high-volume users, with API access available on several paid tiers.

Scribbr is an online plagiarism checker built primarily for students and academic writers, powered by Turnitin's detection engine. It compares submitted text against a wide range of sources, including open and restricted access journals, theses, dissertations, websites, PDFs, and news articles, then returns a similarity score with linked, highlighted matches. Advanced algorithms catch not just exact copying but paraphrasing and synonym swapping, and the tool can flag content that appears to be AI generated.

Rather than a subscription, Scribbr sells single checks priced by document length, plus custom volume pricing for institutions. A unique self plagiarism feature lets writers upload their own unpublished work to compare against. Premium checks also unlock an integrated grammar checker, and submissions are never added to any public database.

Unicheck was a cloud based plagiarism and similarity detection service aimed at schools, universities, and businesses, known for fast scans, citation recognition across APA, MLA, Harvard, Chicago, and Turabian formats, and an AI powered authorship verification tool that could flag inconsistent writing within a single document. It integrated with popular learning platforms such as Canvas, Moodle, Google Classroom, and Schoology, and supported a wide range of file formats and archives.

Turnitin acquired Unicheck and shut the standalone product down on January 1, 2025, ending private and cloud plans and directing former customers toward Turnitin Similarity instead. The historical Personal and Cloud Business plans both started at $15 for the first 100 pages, with custom pricing for K-12 and higher education accounts.

iThenticate is a Turnitin owned plagiarism and similarity checking service built for researchers, authors, and publishers who need to verify originality before publication. It compares manuscripts and grant proposals against a large database of scholarly content accessed through Crossref's network of more than 1,500 publishers, along with CORE open access metadata and ProQuest theses and dissertations. Features include Match Groups for organizing similar sources, a Flags Panel that detects manipulated characters, bulk upload, and side by side comparison.

Pricing is credit based rather than subscription. A Single plan covering one manuscript up to 25,000 words costs $125, a Multiple plan for up to three manuscripts or 75,000 words costs $300, and larger organizations can request custom pricing. Individual plans do not include AI content detection.