NFT Standard
Kalao respects the ERC-721 and ERC-1155 token standards. These are open standards that describe how to build non-fungible tokens on the blockchain. They require your smart contract to return a URI where Kalao can find the NFT metadata. For this, we use the tokenURI function. The contract should return an HTTPS or IPFS URL, which in turn should return a JSON blob of data with the metadata for your token.
The metadata can hold additional properties such as a name, description, and an image.
Kalao supports metadata that is structured according to the official ERC-721 standard:


The Kalao marketplace supports different file formats including images, audio and videos. Each NFT has the following properties:
Image and Animation URL | Images
Supported formats: JPG/PNG/GIF/WEBP Recommended size for images: 500x500 px Videos
Supported formats: MP4, M4V, WEBM Audio
Supported formats: MP3, WAV Maximum file size: 30MB |
External URL | The URL which will appear below the asset's image on Kalao and allows users to view the item on your site. |
Description | A description of the NFT. |
Name | Name of the NFT. |
Attributes | These are the attributes for the NFT, which will show up on the NFT page. |
When creating an NFT on the Kalao marketplace, you will be able to add a name, a description, properties and other information, as well as create a collection to group together related NFTs.

You will be able to view the metadata after creating the NFT.

The metadata is written into the code:

Last modified 8mo ago