AliExpress is an online retail service based in China. The website was launched in 2010 by Alibaba Group, it is made up of small businesses in China and elsewhere, such as Singapore, that offer products to international online buyers at competitive prices.
Aliexpress do not make these product Ids easily visible.
To find Product ID go to the page of necessary product at AliExpress.com and find its digital number in the URL.

- Open Aliexpress.com in a browser.
- See URL
- After the name of the product, You’ll find the product id in the url as visible in the below image.