> ## Documentation Index
> Fetch the complete documentation index at: https://developers.paxoslabs.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Cross-Chain Transfers
> Move PAXGy between Ethereum and X Layer, or mint on Ethereum straight onto X Layer
PAXGy moves between Ethereum mainnet and X Layer over [Chainlink CCIP](https://docs.chain.link/ccip). The tokens are burned on the source chain and issued on the destination. There is no wrapped representation and no liquidity pool.
Two flows:
* **Transfer.** Move PAXGy you already hold, in either direction. `GET /v2/amplify/bridge`
* **Mint and transfer.** Deposit PAXG on Ethereum and receive PAXGy on X Layer, in one transaction. `GET /v2/amplify/deposit` with cross-chain parameters
PAXG exists only on Ethereum, so minting and redemption are Ethereum-only.
Transfers move PAXGy in both directions, but to redeem, the PAXGy has to come
back to Ethereum first.
## Transferring held PAXGy
```bash theme={null}
curl -G "https://api.paxoslabs.com/v2/amplify/bridge" \
-H "x-api-key: pxl_your_key" \
--data-urlencode "vaultAddress=0x6c6494Fd9962eB98B94ffA48F6679058F820700e" \
--data-urlencode "shareAmount=1000000000000000000" \
--data-urlencode "userAddress=0xYourWallet" \
--data-urlencode "chainId=1" \
--data-urlencode "destinationChainId=196" \
--data-urlencode "messageGas=100000"
```
### Parameters
| Parameter | Type | Required | Description |
| -------------------------- | -------- | -------- | -------------------------------------------------------------------------- |
| `vaultAddress` | `string` | Yes | The PAXGy token address |
| `shareAmount` | `string` | Yes | PAXGy to move, in base units |
| `userAddress` | `string` | Yes | Wallet sending the transaction |
| `chainId` | `number` | Yes | Source chain |
| `destinationChainId` | `number` | Yes | Destination chain: `1` for Ethereum, `196` for X Layer |
| `destinationChainReceiver` | `string` | No | Who receives the PAXGy on the destination chain. Defaults to `userAddress` |
| `messageGas` | `string` | Yes | Gas to buy for execution on the destination chain |
### Response
```json theme={null}
{
"transaction": {
"to": "0x41AB5d8387e60E30AACCF11357C306f6d875A6f7",
"data": "0x...",
"value": "431000000000000"
},
"fee": {
"raw": "431000000000000",
"formatted": "0.000431",
"decimals": 18
},
"lane": {
"destinationChainId": 196,
"targetTeller": "0x41AB5d8387e60E30AACCF11357C306f6d875A6f7",
"minimumMessageGas": "0",
"messageGasLimit": "100000"
}
}
```
## The delivery fee must be exact
Cross-chain delivery costs a fee in the **source chain's native token**, on top of gas. It is already set as `transaction.value`, and `fee` reports the same number for display.
Send `transaction.value` exactly as returned. The transaction is rejected
on-chain if the value differs **at all**, including if it is too high, so
padding it "to be safe" will fail. The quote is priced at the current block
and moves with gas conditions: request it again if the user does not confirm
promptly.
Show `fee.formatted` in your confirmation UI. A user approving a transfer sees a native-token charge they did not ask for otherwise.
```typescript theme={null}
const hash = await walletClient.sendTransaction({
to: prepared.transaction.to,
data: prepared.transaction.data,
value: BigInt(prepared.transaction.value), // exact, never rounded or padded
chainId: 1,
})
```
## Choosing `messageGas`
`messageGas` buys execution on the destination chain. Each route accepts a range, returned on every response:
```typescript theme={null}
prepared.lane.minimumMessageGas // "0"
prepared.lane.messageGasLimit // "100000"
```
A value outside that range returns a `400` naming both bounds, so you can correct it without guessing. If you have no reason to pick otherwise, request `messageGasLimit`.
## Minting onto X Layer
Because PAXG only exists on Ethereum, the mint leg always starts there, so `chainId` is `1`. Pass the cross-chain fields to have the PAXGy issued on X Layer instead of Ethereum, in the same transaction:
```bash theme={null}
curl -G "https://api.paxoslabs.com/v2/amplify/deposit" \
-H "x-api-key: pxl_your_key" \
--data-urlencode "vaultAddress=0x6c6494Fd9962eB98B94ffA48F6679058F820700e" \
--data-urlencode "depositAsset=0x45804880De22913dAFE09f4980848ECE6EcbAf78" \
--data-urlencode "depositAmount=1000000000000000000" \
--data-urlencode "userAddress=0xYourWallet" \
--data-urlencode "chainId=1" \
--data-urlencode "destinationChainId=196" \
--data-urlencode "messageGas=100000"
```
Three differences from a plain mint:
* `transaction.value` carries the delivery fee, with the same exactness rule.
* **No mint fee applies** on this route.
* `to` and `permitSignature` are rejected with a `400`. The PAXGy is issued on the destination chain, so a source-chain `to` cannot be honoured. Use `destinationChainReceiver` instead. And a single transaction cannot both consume a permit and transfer across chains, so approve PAXG first.
## Errors
| Status | Cause |
| ------ | ---------------------------------------------------------------------------------------------------------------------------------------------- |
| `400` | No route open to `destinationChainId`, `messageGas` outside the accepted range, or `to` / `permitSignature` combined with `destinationChainId` |
| `403` | This wallet is not permitted to move PAXGy across chains |
| `503` | The chain is unreachable and the fee could not be priced |
A `403` is a property of the wallet, not a transient failure, so retrying will
not help. Cross-chain transfers are enabled per address as part of
[access approval](/v1.0.0/intro/products/paxgy/overview#access).
## Settlement time
The source transaction confirming does not mean the PAXGy has arrived. CCIP finalizes on its own schedule, and the destination balance appears after that. Model the gap explicitly: show the transfer as in-flight and poll the destination balance rather than assuming completion on the source receipt.
## Next
Deposit PAXG and receive PAXGy.
The same transfer without the API.