CardAuthentico is an online marketplace designed for the buying and selling of professionally graded sports cards. The platform focuses on security and trust by requiring identity verification for all users, including government ID checks through a third-party KYC (Know Your Customer) partner. The primary function of the service is to facilitate transactions between verified buyers and sellers, with an emphasis on fraud prevention and dispute resolution. The platform offers several features to support secure trading. All users must complete email verification at signup, and sellers undergo additional KYC screening. The system uses multi-layer verification and advanced fraud detection to block scams before they occur. A dedicated team handles conflict resolution through an arbitration process. Buyers are protected by detailed card authentication and money-back guarantees on purchases. The marketplace also includes an AI-powered search tool that allows users to find cards using natural language queries. Typical use cases involve collectors looking to sell their graded collections or buyers seeking specific cards with confidence in the transaction's safety. The workflow begins with user registration and identity verification. Sellers can then list their cards, while buyers can search using the AI assistant. Trust signals are computed automatically from user activity on the platform, including account age, transaction history, and buyer ratings. These signals are displayed as tiers: Basic (email verified, account in good standing), Enhanced (government ID verified, 5+ completed transactions), and Premium (10+ completed transactions, 95%+ positive feedback, 98%+ fulfillment reliability, no open scam flags). The platform does not require users to upload private documents for these signals, as they are derived from on-platform behavior. CardAuthentico is accessible via its website at cardauthentico.com and does not require any specialized software or hardware to use.