⚡ TL;DR – Why Some Transactions Settle Without a Block
A Zero Confirmation Transaction is a blockchain transaction that has been broadcast to the network but not yet included in a block. It is considered unconfirmed and less secure, as it can still be reversed or replaced. While zero-conf transactions allow for faster interactions, they carry risks—especially in Bitcoin and UTXO-based blockchains—and are not recommended for high-value transfers.
❓ What Is a Zero Confirmation Transaction?
A Zero Confirmation Transaction, also called a 0-conf transaction, is a cryptocurrency transfer that has been submitted to the blockchain network but has not yet been confirmed by miners or validators. In this state, the transaction is visible and may appear in a wallet, but it is not final.
These types of transactions are most relevant on blockchains like Bitcoin, Litecoin, and other UTXO-based networks, where transaction finality depends on block confirmation. In contrast, blockchains like Solana and Ethereum offer faster block times, reducing reliance on zero-conf interactions.
How Do Zero Confirmation Transactions Work?
- Broadcasting – A wallet or dApp sends a transaction to the network.
- Mempool Placement – The transaction enters the mempool, awaiting inclusion in the next block.
- Temporary Acceptance – Some vendors or apps may recognize the transaction before confirmation for speed.
- Finalization – The transaction becomes official after being included in a block and confirmed by the network.
When Are Zero Confirmation Transactions Used?
- Retail Payments – For small transactions like buying coffee with crypto.
- Gaming & Micropayments – Speed is prioritized over full confirmation.
- Lightning Network Routing – Off-chain systems may allow for zero-conf assurance.
- Point-of-Sale (POS) Systems – Merchants may temporarily accept payments without waiting for block confirmation.
What Are the Risks of Zero Confirmation Transactions?
- Double Spend Attacks – A malicious user can send a second transaction to reverse the first.
- Transaction Replacement – Some blockchains allow fee-bumping or RBF (Replace By Fee) to replace unconfirmed transactions.
- No Finality – Until confirmed, the transaction may be dropped or reorganized.
- Unsuitable for Large Transfers – Zero-conf is unsafe for high-value or critical operations.
Are Zero Confirmation Transactions Safe?
It depends on the blockchain and context:
| Blockchain | Zero-Conf Usage | Safety Level |
|---|---|---|
| Bitcoin | Supported but risky (due to RBF) | Low |
| Ethereum | Less common; fast confirmations | Higher |
| Solana | Confirmations in seconds | Higher |
| BNB Chain | Fast blocks, lower zero-conf relevance | Medium |
🔑 Key Takeaways
- A Zero Confirmation Transaction is unconfirmed and exists only in the mempool.
- These transactions are fast but not secure, especially on Bitcoin-like blockchains.
- Double-spending and replacement attacks are key risks.
- They can be useful for low-risk, fast interactions, but not for large-value transfers.
- Solana, Ethereum, and BNB Chain reduce the need for zero-conf due to fast block times.
❓ Frequently Asked Questions About Zero Confirmation Transactions
A zero confirmation transaction (or 0-conf) is a crypto transaction that has been broadcast to the network but not yet confirmed in a block. It’s visible in the mempool and assumed to be valid — but it can still be altered or canceled before confirmation.
No. Until the transaction is included in a block and receives at least one confirmation, it is not finalized. There’s always a risk it could be replaced by a higher-fee transaction (a “double spend”).
They are sometimes used for instant payments, like in retail or gaming contexts, where speed is more important than absolute security. Some merchants accept 0-conf for convenience, but only with low-value payments.
The main risk is double spending — a malicious actor could broadcast two conflicting transactions, and the one with a higher fee might get confirmed while the other is dropped.
Most UTXO-based chains (like Bitcoin and Litecoin) expose zero-conf transactions in the mempool, but not all platforms treat them equally. In Proof-of-Stake chains or account-based models (like Ethereum), 0-conf logic is less prominent or irrelevant.
Generally, no — especially for high-value transfers. For small payments in trusted environments (e.g., between known users), it may be an acceptable risk. Otherwise, it’s best to wait for at least one confirmation.
On Bitcoin, one block is mined every ~10 minutes. On faster chains like Solana or Avalanche, confirmation can take seconds — reducing the need to rely on zero-conf acceptance.
