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Non-transferable NFTs

Non-transferable NFTs, popularized by Vitalik Buterin as soulbound, are NFTs that are useful for reputation tracking: they get added to addresses but are non-transferable, so they cannot be sold and permanently assign some modifier to a given address.

In RMRK this is an especially interesting concept as NFTs can be non-transferable inside another transferable NFT. Thus, an NFT like a Kanaria can have non-transferable gems inside it that give it long lasting benefits and bonuses, but cannot be removed.

This can be further utilized when dealing with in-game avatars and skill systems. A skill can be learned and "installed" into an avatar's brain, but cannot be removed.

In addition to a simple on/off flag, the Kusama implementation (see below) supports temporary transferability and temporary non-transferability which allows a minter to specify that an NFT should be movable only after a certain number of blocks, or not before a certain number of blocks.

Implementations#

The implementations below lead directly to code. For examples of how to utilize them to mint your own NFTs, please refer to the sidebar section for each implementation subtype.

  • Kusama
  • [EVM](in development)
  • [Pallets](in development)