# testmode -> livemode

Winter allows you to create `sandbox` checkouts minting on your testnet smart contract to ensure that the integration is working smoothly. 

Once that is working, you can create a corresponding `livemode` checkout for that project. 

Let's say your test contract is deployed to Mumbai under the address `0xTestContract`. 

You'll create a `sandbox` Winter checkout as follows: 

```
/createProject({
    sandbox: true, // NOTE! This param tells us this is a sandbox project. 
    contractAddress: 0xTestContract,
    ...
    // corresponding test contract info 
})
```

Let's say you get back project ID 10 for this sandbox checkout. You can then test the sandbox checkout via the following URL:

<https://sandbox-winter-checkout.onrender.com/?projectId={PROJECT_ID}>\
\
Let's say that all works (fingers crossed!) and you go ahead and deploy your contract to Polygon Mainnet under the address `0xMainnetContract`.&#x20;

You'll then create a livemode Winter project by calling

```
/createProject({
    projectId: 10 // Send Winter the project ID you got in sandbox
    sandbox: false, // NOTE! This param tells us this is a mainnet project. 
    contractAddress: 0xMainnetContract,
    ...
    // corresponding mainnet contract info 
})
```

Voila! Now you can use that same project ID in livemode as follows: \
[https://checkout.usewinter.com/?projectId={PROJECT\_ID}](https://checkout.usewinter.com/?projectId=666)

Congrats on getting a live, mainnet Winter checkout up and running via API!&#x20;