What are some of the most interesting contracts on Ethereum, where a contract may not necessarily be a system or dApp, but a code snippet? A contract may not have a UI but could still be quite interesting for other reasons.

This question is hard to phrase without losing it's point, but examples of "interesting" could be the way the contract is designed, what it does, how it does it, etc.

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    This a very subjective question; maybe it can be rephrased asking for example usecases of contracts without UI, removing the interesting qualifier. – Joris Bontje Jan 21 '16 at 21:17
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    I tried to define "interesting"... If it's voted down so be it. – eth Jan 21 '16 at 21:37
  • I have to agree with Joris, this is primary opinion based where every answer is equally valid. I will lock and preserve it for historical reasons, though. – Afr Apr 6 '16 at 8:52

Historically Interesting

The first usable contracts were contracts like "Pyramid Schemes" and "find the lowest hash". They were simple, easy to write, and demonstrated the power and flexibility of the blockchain.

Technically Interesting

Shameless self promotion: My own lottery smart-contract was designed to demonstrate RNGs on the blockchain. RANDAO probably did a better job of it though.

In the same vein, the Roulette contract was very interesting in it's mistakes, including relying on a not-so-secret seed and blockhashes/timestamps.


Oraclize.it isn't really a single contract, but it is super useful.

Piper Merriam's Computation Market and Alarm Clock are interesting for their technical use of libraries, and their usefulness.


Ethereum's multisig wallet is interesting for its extensive use of inheritance and modifiers. It's also used to secure a significant amount of Ether (for the Ethereum foundation).

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