UpSign brings a human layer to digital collectibles — letting users sign, personalize, and prove ownership moments directly on-chain. Built on Solana and powered by Metaplex Core, UpSign uses a custom Autograph Plugin that attaches verifiable signatures to NFTs, turning them into unique digital mementos. Each signature is stored immutably on-chain and issues a certificate NFT for both signer and owner, enabling creators, collectors, and event organizers to capture meaningful interactions with transparency, speed, and permanence. UpSign is live on mainnet and expanding toward integrations with DAOs, marketplaces, and brands across the Solana ecosystem. Check it out on already on mainnet: https://www.upsign.fun/