Push Transfer

In a push transfer, the transaction's initiator (the sender) is responsible for signing the transaction, broadcasting it to the network, and covering the associated gas fees or network costs. This is the dominant model for most blockchain transactions, such as sending Ether (ETH) or ERC-20 tokens from one wallet to another. The recipient's wallet address is a passive destination; they do not need to take any action to receive the funds, which appear in their balance once the transaction is confirmed on-chain. This model mirrors traditional digital payment systems where the payer initiates the transfer.

This model contrasts sharply with a pull transfer, where the recipient initiates the transaction. In pull systems, the recipient is granted a pre-approved allowance or a signed authorization (like an EIP-2612 permit) and subsequently pulls the funds from the sender's account, often paying the gas fee themselves. Push transfers are simpler for basic payments but can be less efficient for recurring or automated payments, where pull mechanisms reduce transaction overhead and improve user experience by batching operations.

The security model of a push transaction is straightforward: the sender must possess the private key to sign the transaction and have sufficient native currency to pay fees. Once broadcast, the transaction is immutable and can be traced on the public ledger. However, a key limitation is that if the sender makes an error in the recipient's address, the funds are typically irretrievable, as there is no central authority to reverse the transaction. This underscores the importance of address verification in push-based systems.

Push transfers are fundamental to Decentralized Finance (DeFi) and Non-Fungible Token (NFT) marketplaces for one-time purchases and peer-to-peer payments. For example, buying an NFT on a primary sale usually involves the buyer pushing payment to a smart contract. Their efficiency makes them ideal for direct, discretionary payments but less so for subscription services or decentralized payroll, where pull-based meta-transactions or gasless transactions are often implemented to abstract fee payment from the end-user.

In a push transfer, the transaction's originator, or sender, is the active party who initiates the transfer and covers the gas fee (or network fee) required for the transaction to be processed and recorded on the blockchain. This is the most common model for transferring assets like Ether (ETH), ERC-20 tokens, or NFTs. The process is analogous to sending an email or a traditional wire transfer, where you must know the recipient's exact address and possess the necessary funds to pay the transaction cost. The recipient's wallet is entirely passive in this model, requiring no action to receive the funds.

The technical flow involves the sender creating, signing, and broadcasting a transaction to the network. This transaction contains critical data: the recipient's public address, the amount or asset identifier to send, and the designated gas fee. Miners or validators then include this transaction in a new block. Crucially, because the sender pays the fee, they control the transaction's priority; a higher fee typically results in faster confirmation. This model contrasts sharply with a pull transfer, where the recipient initiates and pays for the transaction to withdraw approved funds from the sender's address, a common pattern in subscription or allowance-based systems.

Push transfers are the backbone of most user-facing cryptocurrency transactions. Common examples include sending payment to a friend's wallet address, purchasing an item from an online store, or depositing funds to a centralized exchange. Their security relies on the sender's accuracy; once broadcast, a transaction to an incorrect address is generally irreversible. This model's simplicity for the recipient—who receives funds without signing a transaction—makes it ideal for one-time payments, donations, and any scenario where the payer is expected to bear the cost of the transfer.