Although cryptocurrency markets have taken a hit this summer, non-fungible tokens, or NFTs, have remained as popular as ever. In the first half of 2021, sales of the tokens, which are marketed as one-of-a-kind digital artefacts, exceeded $2.5 billion. Ripple, whose fate is tied to the XRP ledger, said last week that it has invested in Mintable in a Series A round. Mintable is a website that provides easy-to-use tools for creating NFTs.