# Use cases

1. API — provides a list of supported blockchains as well as a list of tokens for a destination network upon request GET `v1/tokens/allForSwapAndBridge` 
2. API — provides a list of tokens for a “departure” network upon request POST `v2/tokens/list`.
3. API (optional) — provides calculated gas price values in GWEI (nAVAX for Avalanche) for fast, medium, low transaction time GET `v1/{chainID}/gasprices` (in the example GET `v1/1/gasprices` - chainID=fromChainID)
4. GUI — the user selects the networks and tokens the exchange is made between. For example, for an Ethereum -> Polygon swap, the parameters will be:
   1. fromChainID = 1; toChainID = 137
   2. fromTokenAddress = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 (USDC) 
   3. toTokenAddress = 0x8f3Cf7ad23Cd3CaDbD9735AFf958023239c6A063 (DAI)
5. GUI — the user enters a sale amount.
6. GUI (optional) — the user selects the gas price value from #3.
7. GUI — the user sets the slippage tolerance value as a percentage. The recommended value is 1%.
8. API — endpoint GET `v1/price` provides the number of tokens that the user will receive for the purchase.
9. GUI — the user connects the wallet.
10. API — endpoint GET `v1/{chainID}/transaction/allowance` (GET `v1/1/transaction/allowance`) returns the amount of tokens that the exchange smart contract has access to (not required for native coins, chainID = fromChainID).
11. GUI — if the value of the sale is greater than the value from #10, the user is prompted to provide access for the tokens exchange (otherwise the exchange transaction will not be processed).
12. API — endpoint GET `v1/{chainID}/transaction/approve` returns the input parameters (calldata) for a transaction to provide access to tokens, and the address of the contract where the transaction should be sent to.
13. GUI — generates an unsigned transaction based on the data from #12 and sends it to the user's connected wallet.
14. WALLET — the user confirms the operation in the wallet, and the wallet then signs the transaction and sends it to the blockchain.
15. GUI — after successful confirmation of the transaction from #14, the user is offered a button to exchange the selected tokens.
16. API — by endpoint GET `v1/quote` provides the number of the tokens purchased, transaction input parameters.
17. GUI — generates an unsigned transaction based on the data from #16 and sends it to the user's connected wallet.
18. WALLET — the user confirms the operation in the wallet, and the wallet then signs the transaction and sends it to the blockchain.

{% hint style="info" %}
The endpoints `v1/price` and `v1/quote` can also be used for swaps within the same blockchain network. Just specify the same blockchain identifier for parameters <mark style="color:orange;">fromChainID</mark> and <mark style="color:orange;">toChainID</mark>.
{% endhint %}


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