Checking a dynamic NFT

Before you collect an NFT, it helps to know if it can change. The ledger answers three questions.

1. Can it change?

Every NFT carries its settings in the open. One of them is Mutable. If Mutable is on, the issuer can replace the URI. If it is off, the URI is fixed for good.

Mutable is not good or bad. A game item that levels up needs it. A piece of art sold as final probably should not have it. What matters is that the setting matches what the issuer told you.

2. Who can change it?

Two accounts at most: the issuer, and one authorized minter if the issuer has named one. Both are visible on the ledger. If the issuer has disabled all its keys and has no minter, nobody can send the change.

3. Has it changed before?

Every update is a transaction, and transactions are permanent public records. A tool that reads an NFT's history can list each one.

So a dynamic NFT keeps a paper trail. You can see what it pointed to last month and what it points to now.

Read the flag. Call nft_info on a Clio server with the nft_id. The flags field is a bit map:

A value of 24 is transferable and mutable. A value of 8 is transferable and not mutable. account_nfts returns the same bits as Flags for each NFT an account holds.

The first four hex digits of the NFTokenID are the flags as well. An ID that starts 0018 has flags 24.

Find who can modify. nft_info returns issuer. Call account_info on that address. If the AccountRoot has an NFTokenMinter field, that account can also send NFTokenModify.

Read the history. nft_history on a Clio server takes an nft_id and returns the successful transactions that touched the NFT. Look for entries with TransactionType of NFTokenModify. Each one carries the URI it set, or no URI if it cleared the field.

Read the current URI. nft_info returns uri for an NFT that has one. account_nfts returns URI in hex.

What a modify cannot do. It cannot move the NFT, change the transfer fee or change the flags. If an app shows a different fee or collection after an update, the app is wrong or it is showing a different NFT. Compare the NFTokenID.

Related: Checking a collection.