Zucoin transfer codes and transactions

9 August 2026

A Zucoin transfer code carries instructions or transaction data between people, wallets, websites, and services. A transaction contains the signed change between the sender and receiver.

The transfer code helps a wallet start or continue a transfer. It is not, by itself, proof that a transaction is complete.

What is a Zucoin transfer code?

Transfer Code v1 is an encoded JSON object. Its type tells the wallet what action to prepare, and its incoming_data contains the data for that action.

A sender-create transfer code asks a wallet to prepare a transfer. This unencoded example requests 0.005 Zucoin for a receiver:

{
  "version": "1",
  "type": "sender_create_transaction",
  "incoming_data": {
    "receiver_key_public__base64urlsafe": "RECEIVER_PUBLIC_KEY...",
    "inner_state_amount": "0.005",
    "message": "Invoice #1042",
    "user_share_message": "Check the invoice before you continue"
  }
}

The Transfer Code v1 action types used here are:

• sender_create_transaction: prepare a transfer from the wallet that opens the code.
• sender_create_transaction_explicit: prepare a transfer from the exact sender wallet address supplied in the code.
• receiver_confirm_partial_transaction: give the receiver a sender-signed partial transaction to inspect and confirm.

The sender must review and confirm a transfer prepared by a sender-create code. A transfer code cannot silently complete the transfer.

The wallet copies the optional message value into inner.message when it prepares Transaction v2. The optional user_share_message is for instructions shown around the transfer flow. It stays in the transfer code and is not copied into the signed transaction.

What is a Zucoin transaction?

A current Zucoin transaction uses Transaction v2. The inner object contains the transaction data that the wallets validate and sign. The sender adds step_1_signature. The receiver checks that partial transaction and adds step_2_signature.

This simplified example shows the current Transaction v2 structure. The public keys and signatures are placeholders. Optional fields are included to show where they belong.

{
  "inner": {
    "type": "unique_combinable",
    "version": "2",
    "unix_time_secs": "1786255200.123456",
    "signer_steps": 2,
    "step_1_signer": "sender",
    "step_2_signer": "receiver",
    "step_1_key_public__base64urlsafe": "SENDER_PUBLIC_KEY...",
    "step_2_key_public__base64urlsafe": "RECEIVER_PUBLIC_KEY...",
    "step_1_state": {
      "amount": "94.995"
    },
    "step_2_state": {
      "amount": "5.005"
    },
    "previous_step_1_state_signature": "PREVIOUS_SENDER_TRANSACTION_SIGNATURE...",
    "previous_step_2_state_signature": "PREVIOUS_RECEIVER_TRANSACTION_SIGNATURE...",
    "expiry__unix_time_secs": "1786258800",
    "message": "Invoice #1042"
  },
  "step_1_signature": "SENDER_SIGNATURE...",
  "step_2_signature": "RECEIVER_SIGNATURE..."
}

The state amounts and time values are text strings. This preserves the required decimal precision. The two previous-state signature fields connect each wallet state to its latest applicable settled transaction.

expiry__unix_time_secs and message are optional. Omit an optional field when it is not needed.

Partial and complete transactions

A partial Transaction v2 contains the transaction inner data and the sender's step_1_signature. A complete Transaction v2 also contains the receiver's step_2_signature.

The receiver confirms the exact sender-signed data. If important transaction data changes, the signatures must be created again for that data.

More on this topic

Create a pre-formed sender transfer code with JavaScript DOM

Create a pre-formed sender transfer code with PHP

How do Zucoin transactions work?

Inspect a Zucoin transfer code

Disclaimer: Of course, this is not advice, financial or otherwise. It’s also important to consider the risks and challenges associated with any potential benefits.