Smart contracts can be public, which opens up the possibility to prove functionality, e.g. self-contained provably fair casinos.
One issue related to using smart contracts on a public blockchain is that bugs, including security holes, are visible to all but cannot be fixed quickly. One example of this is the 17 June 2016 attack on The DAO, which could not be quickly stopped or reversed.
There is ongoing research on how to use formal verification to express and prove non-trivial properties. A Microsoft Research report noted that writing solid smart contracts can be extremely difficult in practice, using The DAO hack to illustrate this problem. The report discussed tools that Microsoft had developed for verifying contracts, and noted that a large-scale analysis of published contracts is likely to uncover widespread vulnerabilities. The report also stated that it is possible to verify the equivalence of a Solidity program and the EVM code.
Ethereum blockchain applications are usually referred to as DApps (decentralized application), since they are based on the decentralized Ethereum Virtual Machine, and its smart contracts. Many uses have been proposed for Ethereum platform, including ones that are impossible or unfeasible. Use case proposals have included finance, the internet-of-things, farm-to-table produce, electricity sourcing and pricing, and sports betting. Ethereum is (as of 2017) the leading blockchain platform for initial coin offeringprojects, with over 50% market share.
As of January 2018, there are more than 250 live DApps, with hundreds more under development. Project applications listed in this section are not exhaustive and may be outdated.
- Digital signatures that ensure authenticity and proof of existence of documents: the Luxembourg Stock Exchange has developed such a system
- Slock.It is developing smart locks
- Digital tokens pegged to fiat currencies: Dai, stablecoin pegged to US dollar. Decentralized Capital. Spanish bank Santander is also involved in such a project.
- Digital tokens pegged to gold: Digix
- Improved digital rights management for music: Imogen Heap used the technology
- Platforms for prediction markets: Augur, Gnosis Stox
- Platforms for crowdfunding: the DAO Social media platforms with economic incentives: Backfeed, Akasha
- Decentralized marketplaces: FreeMyVunk, TransActive Grid
- Remittance: Everex
- Online gambling: CoinPoker, Etheroll
- Electric car charging management: RWE
- Secure identity systems for the Internet: uPort
- Labour economics: Blocklancer, Ethlance
- Video Games: Cryptokitties popularity in December 2017 caused the Ethereum network to slow down.