GlossaryWhat does onchain mean?
What does onchain mean?
Onchain means recorded in a blockchain's own ledger, the shared record every full node keeps and anyone can check. Bitcoin's ledger is at block 975,293 at this check, according to mempool.space, and every transaction in those blocks is onchain.
What Onchain Means in Crypto
Onchain in crypto means a piece of data, usually a transaction, sits inside a block that the network has accepted. Once it is there, any node can replay it, any block explorer can show it, and changing it would mean rewriting the chain itself.
That is why people say a payment is final once it is onchain and buried under more blocks. A transaction that has been sent but not yet mined is still waiting. On Bitcoin, 71,084 transactions sit in that queue right now, in what is called the mempool, and the fastest fee rate mempool.space suggests is 1 sat/vB.1
Onchain data is public by design. Balances, transfers and smart contract calls can all be read by anyone with the wallet address or transaction ID, which is what analysts mean by onchain data.
Onchain vs Offchain: The Difference
Onchain vs offchain comes down to where the record lives: onchain records sit in the blockchain's ledger, while offchain records are kept somewhere else and may or may not settle to the chain later.
Offchain does not mean fake, and the crypto glossary uses both words throughout. It means the chain is not the source of truth for that step. An exchange's internal database, a Lightning channel between two people and the execution layer of a rollup are all offchain systems that lean on a blockchain in different ways.
| Activity | Onchain or offchain | Why |
|---|---|---|
| Sending BTC from your wallet to another address | Onchain | The transaction is mined into a Bitcoin block |
| Transfer between two Binance accounts | Offchain | Binance shows the TxID as [Internal], with no blockchain transaction |
| Withdrawing from an exchange to your own wallet | Onchain | The exchange broadcasts a network transaction and pays a network fee |
| Opening a Lightning channel | Onchain | A funding transaction goes to a 2-of-2 multisig address |
| Paying through an open Lightning channel | Offchain | Commitment transactions are not recorded onchain |
| Closing a Lightning channel | Onchain | The closing transaction is published to Bitcoin |
| A swap on a rollup | Offchain execution, data posted onchain | The rollup posts its transaction data to Ethereum |
Exchange Transfers Are Usually Offchain
Exchange transfers between two users of the same exchange are usually offchain: the exchange simply edits its own ledger. Binance says internal transfers between Binance accounts carry zero transaction fees, are credited immediately and show the TxID as [Internal] instead of a blockchain hash, according to Binance's internal transfer FAQ.
The moment coins leave for an outside address, the transfer goes onchain. Binance charges the network fee only for withdrawals to non-Binance addresses, because only those need a real blockchain transaction.
Is a Layer 2 Transaction Onchain
A layer 2 transaction is onchain on the layer 2 chain and offchain from the point of view of the base layer until its data is posted there. ethereum.org explains that rollups execute transactions outside Ethereum layer 1, bundle hundreds of them into one layer 1 transaction and post the data to Ethereum, so reverting them would mean reverting Ethereum itself, as described on ethereum.org's layer 2 guide.
Optimistic rollups assume transactions are valid unless challenged with a fault proof. ZK rollups post a validity proof to Ethereum mainnet. The layer 2 explainer covers the two designs in more detail.
Lightning Shows Onchain and Offchain Working Together
Lightning shows onchain and offchain working together: the channel opens and closes onchain, and the payments in between stay offchain. Lightning Labs describes a funding transaction broadcast to a 2-of-2 multisig address, then balance updates through commitment transactions that are never announced or recorded onchain, in steps as small as one millisatoshi.4
When the two sides are done, they sign a closing transaction and publish it to Bitcoin. If one side disappears, the other can force close with the latest commitment transaction, which is also onchain.
Questions People Ask About What does onchain mean
These are the questions people ask next about what does onchain mean.
What does onchain mean in crypto?
Onchain in crypto means recorded in a blockchain's ledger, inside a block the network has accepted. Anyone running a node or using a block explorer can see an onchain transaction, and reversing it would mean rewriting the chain.
What does offchain mean?
Offchain means the record is kept somewhere other than the blockchain's ledger, such as an exchange database, a Lightning channel or a rollup's execution layer. Some offchain activity later settles onchain, such as a Lightning channel close or a rollup batch posted to Ethereum.
Is onchain or on-chain the right spelling?
Onchain, on-chain and on chain are all spellings of the same word, and they mean the same thing. Lightning Labs' channel docs mostly write on-chain with a hyphen. This site writes onchain and offchain as single words.
Are transfers on an exchange onchain?
Transfers on an exchange between two of its own users are usually not onchain. Binance, for example, shows the TxID of an internal transfer as [Internal] and charges no transaction fee. Withdrawals to an outside address are onchain and pay a network fee.
Why do onchain transactions cost a fee?
Onchain transactions cost a fee because they take up space in a block, and block space is limited. On Bitcoin the fast fee rate is 1 sat/vB at this check, per mempool.space. The gas fees page explains how Ethereum prices the same thing.
Sources
Every number on this page comes from these sources, checked November 10, 2026.