# Bridge

A crosschain bridge is an asset exchange between networks. For example, you have **USDT** on the **Ethereum** network, and you want them to be on the **Tron** network.

To conduct an asset exchange between networks, you need to make sure that this service is available in the networks you have chosen. To do this, request [list of available coins](#e4658fd5-5daf-4689-b845-663f8ed93470), find the coin you need, it will have a list of `networks` networks, make sure that the flag `allowCrosschainBridge` for the networks you need is set to `true`

Find out the [allowable limit](#221a78cc-5f4d-445f-b57c-ca66d32fbbda) for the transaction amount. Please note that the limit amounts are indicated in **USD**, the rates of such stablecoins as **USDT**, **BUSD** etc do not differ significantly from the rate of **USD**, and if you want to exchange another coin, then you will need to get the exchange rate to **USD** to make sure that your amount meets the specified limits.

Request [fee preview](#f67f6d22-45af-40c8-8590-537b521213be) to get a `token`, it will need to be specified when [requesting transaction creation](#9676abb2-8dba-4707-85de-547d03ed16df) as `feeToken`.

The operation is not executed immediately after the request, you must wait 1-3 minutes. You can [find out the operation execution status](#3a3f4de2-f83d-491f-9294-c9d72705c65e) yourself, or you can specify the URL to receive the [webhook](#webhooks) in the `webhookUrl` field when creating.

Available statuses

| **Статус** | **Описание**           |
| ---------- | ---------------------- |
| CREATED    | Request registered     |
| PENDING    | Being processed        |
| ERROR      | Error during execution |
| REJECTED   | Request denied         |
| PROCESSED  | Success                |

## API Interaction Scheme

{% @mermaid/diagram content="sequenceDiagram
Merchant ->> Onchainpay: Request fee token
Onchainpay ->> Merchant: Fee token
Merchant ->> Onchainpay: Creating operation
Onchainpay ->> Merchant: Operation body

```
Note over Onchainpay: Processing operation

Onchainpay -->> Merchant: Operation result webhook" %}
```