# How to Create Free Mint NFT Rewards with Callback Verification
With the successful integration of the API callback, winners will be able to mint their own NFT on your website via a specific URL containing their track\_id and eligibility.
**Please follow the steps to create Free Mint NFT reward and to integrate API callback.**
**Step 1**
Enter a reward name, number of winners, and upload an image of that reward.
**Step 2**
After that, you will need to get url params (something like track\_id=Edg1Y475BiU) from your website and parse out the trackId.
**About track\_id:**
* TrackId is necessary to detect the user's participation in the task and to verify it. We will detect when a user clicks to participate in the task, the ?trackId={{trackId}} will be used for detection.
* You will see the ?trackId={{trackId}} applied to your website link:
If your website link is
the visitors may come to your site via the link
**Step 3**
Next, please copy the API key we provide you to integrate it with your website.
Then enter the parameters according to the rules of const data, and encrypt the whole const data using the standard **HmacSHA256** algorithm.
**Step 4**
Use our official API below and pass the corresponding parameters in the following code.
**Official API:**
```javascript
const api_key = "3lhpTSAJd6XDgBe4XWcozob4iMmYUlkPc9c4fwnoydGk4Bh5lSA3qrSiqgXeJcX7"; // your api_key
const { track_id} = queryString.parse(location.search);
const timestamp=new Date().getTime()
const data = `track_id=${track_id}×tamp=${timestamp}`
const sign = crypto.HmacSHA256(data, api_key).toString(); // HmacSHA256
fetch("https://cwallet.com/cctip/v1/giveaway/player/status", {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify({
track_id,
sign,
timestamp,
}),
}).then(async (res) => {
console.log(await res.json());
});
```
**Step 5**
After the above steps are completed, enter your website link and click the ‘Check API callback’ to test it.
**Note:**
Each project you created on Cwallet Giveaway Tool will have a unique API key, and it will not change. So you only need to integrate once for a website. Also, you will be able to create Free Mint NFT reward on multiple websites if you need to.
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