PlagiarismGuard: Democratizing Academic Integrity with a Free, Open-Source, Multi-API Plagiarism Detection Ecosystem

Academic integrity is facing an unprecedented crisis in the digital era, exacerbated by the proliferation of "paper mills" and the rapid adoption of sophisticated Generative AI tools. While commercial detection solutions like iThenticate and Turnitin have established themselves as industry standards, their prohibitive cost models create a significant "integrity divide," disproportionately affecting institutions in low- and middle-income countries (LMICs) and independent researchers. This unavailability of affordable verification tools risks compromising the quality of scientific output from resource-constrained regions. Addressing this disparity, we present PlagiarismGuard, a free, open-source, client-side academic integrity verification platform. Built on a modern serverless architecture, PlagiarismGuard aggregates search results from 16 open academic databases—including OpenAlex, Semantic Scholar, and CrossRef—to perform comprehensive similarity analysis without requiring institutional subscriptions. The system implements advanced text fingerprinting algorithms (n-gram shingling), code plagiarism detection (Winnowing), and perceptual image hashing, while also integrating a "Bring Your Own Key" (BYOK) model for AI-powered authorship analysis using models like Google Gemini and OpenAI GPT-4. We detail the system's architecture, privacy-preserving client-side processing model, and performance benchmarks, demonstrating that open-source alternatives can provide robust plagiarism detection capabilities comparable to commercial tools. By releasing PlagiarismGuard under the MIT License, we aim to democratize access to academic integrity tools and foster a community-driven approach to combating research misconduct.