coinscrum-presents-Metadata in the Blockchain: The OP_RETURN Explosion


coinscrum-presents-Metadata in the Blockchain: The OP_RETURN Explosion

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Metadata in the Blockchain: The OP_RETURN Explosion

Presented Gideon Greenspan, Founder and CEO, Coin Sciences Ltd (

Just over a year ago, Bitcoin Core introduced an official mechanism for embedding arbitrary metadata in transactions, called OP_RETURN. This transformed bitcoin into a low-level protocol on which many decentralised applications can be built. Since then, OP_RETURN metadata has been growing exponentially, with uses including document notarisation, colored coins, messaging and permanent data storage .In this talk well begin by reviewing the history of metadata in the blockchain and its underlying economic rationale. We’ll then consider what types of applications it is suitable for, and look at some which are already growing rapidly in use.We’ll finish by presenting CoinSpark ( ), an open source protocol for enhancing bitcoin transactions which makes extensive use of OP_RETURNs. Since OP_RETURNs are currently limited to 40 bytes, well discuss some of the technical tricks that CoinSpark uses to maximize the value of those few precious bytes.

18:30hrs – Doors open, 19:00hrs – Presentation begins, 20:00hrs – Networking / beer, 21:00hrs – Ends


2015-04-30, 18:00hrs


Barclays Accelerator, 81 Palace Gardens Terrace, London, W8 4AT