> For the complete documentation index, see [llms.txt](https://docs.tuum.tech/hedera-wallet-snap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tuum.tech/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis/hedera-token-service-apis/hts-initiateswap.md).
# hts/initiateSwap
## How to call the API from an app
Hedera Wallet Snap connects to your currently connected Metamask account by default. To learn how apps can connect to Hedera Wallet Snap using a non-metamask(external) account, refer to this [documentation](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis.md#connecting-to-a-non-metamask-external-account).
Then, depending on whether you're trying to connect to a metamask account or a non-metamask account, you can call the snap API in the following way:
```tsx
const snapId = `npm:@hashgraph/hedera-wallet-snap`
const initiateSwapAPI = async () => {
const externalAccountParams = {
externalAccount: {
accountIdOrEvmAddress: '0.0.12345',
curve: 'ED25519'
}
}
const requester = {
assetType: 'HBAR', // 'HBAR' | 'TOKEN' | 'NFT'
to: '0.0.1',
amount: 1
}
const responder = {
assetType: 'TOKEN', // 'HBAR' | 'TOKEN' | 'NFT'
amount: 10,
assetId: '0.0.4279119' // For NFT, the format is tokenId/serialNumber
}
await window.ethereum.request({
method: 'wallet_invokeSnap',
params: {
snapId,
request: {
method: 'hts/initiateSwap',
params: {
network: 'testnet',
atomicSwaps: [{
requester,
responder
}],
memo?: // Optional param - type string
maxFee?: // Optional param - type number(in hbars)
/*
Uncomment the below line if you want to connect
to a non-metamask account
*/
// ...externalAccountParams
}
}
}
})
}
```
{% hint style="info" %}
* Both the requester and responder must be passed
* You can have multiple atomic swaps as part of the same transaction with multiple requester and responder but all the parties must call the [`hts/completeSwap`](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis/hedera-token-service-apis/hts-completeswap.md) API to complete the transaction or the transaction will fail
* The `responder` must must sign the transaction by calling [`hts/completeSwap`](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis/hedera-token-service-apis/hts-completeswap.md) API within 30 minutes or the transaction will fail
* Swap cannot be initiated with the same token. So, for example, requester cannot try to swap 1 Hbar with the responder for 10 Hbar
{% endhint %}
## What the API does
1. Retrieves the currently connected account the user has selected on Metamask. If it's the first time, a new [snap account](/hedera-wallet-snap/hedera-wallet-snap/snap-account.md) is created and the account info is saved in snap state.
2. Parses the arguments that were passed
3. Uses [scheduled transaction](https://docs.hedera.com/hedera/sdks-and-apis/sdks/schedule-transaction/create-a-schedule-transaction) to implement the atomic swap feature whereby the `requester` initiates the swap with the `responder` by calling this API upon which the snap sends this transaction as a scheduled transaction to the ledger. Within 30 minutes, if the `responder` calls the [`hts/completeSwap`](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis/hedera-token-service-apis/hts-completeswap.md) API with the scheduleId of the transaction, the swap is complete.
4. Returns the transaction receipt as response
## Example of how the Atomic Swap is performed
Let's assume Alice wants to swap her 1 Hbar with 10 Tuum token that Bob has(basically a peer to peer swap)
1. Alice calls the snap API for `hts/initiateSwap` and as part of the parameters, she says she wants to give her 1 Hbar to Bob if Bob can give Alice 10 Tuum tokens
2. Snap creates this atomic swap transaction and sends it to the network as a scheduled transaction with a max expiry of 30 minutes
3. Snap returns the schedule Id for this transaction
4. Alice lets Bob know about this atomic swap transaction and gives him the schedule Id
5. Bob queries the schedule Id and verifies everything looks good
6. Bob calls the snap API for [`hts/completeSwap`](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis/hedera-token-service-apis/hts-completeswap.md) with the schedule Id
7. The scheduled transaction is executed and the atomic swap transaction is complete
An example response:
```json
{
"currentAccount": {
"metamaskEvmAddress": "0x0b3628d1b838993b5fceec8b2a26502e7a8e5241",
"externalEvmAddress": "",
"hederaAccountId": "0.0.3581604",
"hederaEvmAddress": "0xca53f9c93d30e0b7212d67901e5a24fb090d542b",
"publicKey": "0x0206022cea4c6dd6d2e7263b8802253971de922f5380661d97cba82dee66f57ad6",
"balance": {
"hbars": 88.13421155,
"timestamp": "Fri, 26 Apr 2024 17:50:12 GMT",
"tokens": {
"0.0.4279119": {
"balance": 50,
"decimals": 1,
"tokenId": "0.0.4279119",
"name": "NewTuum",
"symbol": "NEWTUUM",
"tokenType": "FUNGIBLE_COMMON",
"supplyType": "INFINITE",
"totalSupply": "50",
"maxSupply": "0"
}
}
},
"network": "testnet",
"mirrorNodeUrl": "https://testnet.mirrornode.hedera.com"
},
"receipt": {
"status": "SUCCESS",
"accountId": "",
"fileId": "",
"contractId": "",
"topicId": "",
"tokenId": "",
"scheduleId": "0.0.4285081",
"exchangeRate": {
"hbars": 30000,
"cents": 333977,
"expirationTime": "Fri, 26 Apr 2024 20:00:00 GMT",
"exchangeRateInCents": 11.132566666666667
},
"topicSequenceNumber": "0",
"topicRunningHash": "",
"totalSupply": "0",
"scheduledTransactionId": "0.0.3581604@1714159254.939190271?scheduled",
"serials": [],
"duplicates": [],
"children": []
}
}
```
## Live Demo on CodePen
{% embed url="" %}
{% hint style="info" %}
* **Note**: Visit to activate your hedera account before you interact with the demo
* If you're getting any errors with the live demo, make sure you go through the [FAQs](/hedera-wallet-snap/basics/faqs.md) section to learn about what you may be missing. You need to install [Metamask](https://metamask.io/) in your browser for the live demo to work.
* To ease the integration of Hedera Wallet Snap on an application, we have created a template web application that you can run locally and check out the code in its entirety to learn how you can integrate and interact with various APIs exposed by Hedera Wallet Snap. Check out the full source code at [template application github repository](https://github.com/hashgraph/hedera-metamask-snaps/tree/main/packages/hedera-wallet-snap/packages/site).
* You can also check out the [API reference](/hedera-wallet-snap/hedera-wallet-snap/snap-rpc-apis.md) to learn how each API works.
{% endhint %}
---
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