FAQ

Why does the Core account have both on-chain and off-chain data?

The Core contains on-chain data, yet it also has a URI attribute which points to an off-chain JSON file which provides additional data. So why is that? Can't we just store everything on-chain? Well, there are several issues with that:

• We have to pay rent to store data on-chain. If we had to store everything within the Metadata account, which may include long texts such as the description of an asset, it would require a lot more bytes and minting an asset would suddenly be a lot more expensive.
• On-chain data is much less flexible. Once an account is created using a certain structure, it cannot easily be changed. Therefore, if we had to store everything on-chain, the standard would be a lot harder to evolve with the demands of the ecosystem.
• If needed you can add additional on-chain data using the attributes plugin. It will store the data in the asset account and even be indexed in DAS.

Therefore, splitting the data into on-chain and off-chain data allows us to get the best of both worlds where on-chain data can be used by the program to create guarantees and expectations for its users whereas off-chain data can be used to provide standardized yet flexible information.

Are there any costs to using Core?

Token Metadata currently charges very small fee of 0.0015 SOL per Asset mint to the caller. More details can be found on the Protocol Fees page.

How to create a Soulbound Asset?

The Core Standard allows you to create Soulbound Assets. To achieve this you should use the PermanentFreeze plugin. On creation you would set the Asset to be frozen without authority, so that it can not be thawed.

import { createAsset, pluginAuthorityPair, nonePluginAuthority } from '@metaplex-foundation/mpl-core'

await createAsset(umi, {
  owner,
  plugins: [
    pluginAuthorityPair({
      type: 'PermanentFreeze',
      data: { frozen: true },
      authority: nonePluginAuthority(),
    }),
  ],
})

How to set an Asset to be Immutable?

coming soon

What are the differences between Metaplex Token Metadata and Core?

There are quite many differences. For example Core is cheaper, requires less Compute Units and should be easier to work with from a developer perspective. Have a look at the differences page for details.