The DApp is called “Document Registry” and is simple: it holds a set of documents and can confirm the existence of certain document (e.g. course certificate, diploma of graduation or loan contract) at certain date in the past. The DApp uses the decentralized storage system IPFS to hold the document contents and keeps their hashes on the blockchain (in the Ropsten Testnet for the demo).
Source code: https://github.com/nakov/Ethereum-Web3-Document-Registry-Demo
Blog post: https://nakov.com/blog/2018/10/11/svetlin-nakov-speaker-blockchain-economy-istanbul-summit-2019/