The primary object in the OpenSea API is the asset, which represents a unique digital item whose ownership is managed by the blockchain. The below CryptoSaga hero is an example of an asset shown on OpenSea.

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Here's an overview of some of the fields contained in an asset:

Field name	Description
token_id	The token ID of the NFT
image_url	An image for the item. Note that this is the cached URL we store on our end. The original image url is `image_original_url`
background_color	The background color to be displayed with the item
name	Name of the item
external_link	External link to the original website for the item
asset_contract	Dictionary of data on the contract itself (see asset contract section)
owner	Dictionary of data on the owner (see account section)
traits	A list of traits associated with the item (see traits section)
last_sale	When this item was last sold (null if there was no last sale)

Traits

Traits are special properties on the item, that can either be numbers or strings. Below is an example of how OpenSea displays the traits for a specific item.

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Here are some of the fields contained in a trait:

trait_type	The name of the trait (for example color)
value	The value of this trait (can be a string or number)
display_type	How this trait will be displayed (options are `number`, `boost_percentage`, `boost_number`, and `date`). See the adding metadata section for more details

Asset contracts

Asset contracts contain data about the contract itself, such as the CryptoKitties contract or the CoolCats contract. Here are the field associated with an asset contract:

address	Address of the asset contract
name	Name of the asset contract
symbol	Symbol, such as CKITTY
image_url	Image associated with the asset contract
description	Description of the asset contract
external_link	Link to the original website for this contract