The rapid development of financial technology has encouraged the emergence of online lending services that provide easier access to financing through digital platforms. However, along with the growth of legal platforms supervised by the Financial Services Authority (OJK), many illegal online lending services have also emerged and caused various legal problems. This study aims to analyze the differences between legal and illegal online lending from the perspective of economic law, particularly in terms of legality, operational mechanisms, consumer protection, and regulatory supervision. The research uses a normative juridical method with a statutory and conceptual approach. Data were obtained through library research by examining relevant laws, regulations, and academic literature related to fintech lending. The results show that legal online lending operates under clear regulations and supervision from OJK, requiring transparency, accountability, and consumer protection, including personal data protection. In contrast, illegal online lending operates without authorization and often involves excessive interest rates, lack of transparency, and abusive collection practices. From the economic law perspective, strengthening regulation, supervision, and financial literacy is essential to ensure consumer protection and support sustainable fintech development.