What is OpenSea?

Open­Sea serv­es as a hor­i­zon­tal, peer-to-peer mar­ket­place for digi­tal goods, allowing users to buy, sell, and auction NFTs, rare digital items and crypto collectibles. For developers, OpenSea of­fers ex­ten­sive in­te­gra­tions and tool­ing for dApps in the NFT space. They in­dex and pro­vide the largest dataset of NFTs (hav­ing been around since the first projects were listed), and act as a sec­ondary mar­ket for pop­u­lar col­lec­tions and projects. 
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Open­Sea sup­ports a num­ber of wide­ly-used to­kens and chains, and they are ac­tive­ly expand­ing that list. They sup­port both ERC-721 non-fun­gi­bles and ERC-1155 semi-fun­gi­bles, and are a mul­ti-chain plat­form, pro­vid­ing tool­ing for Poly­gon and Klaytn in ad­di­tion to Ethereum.
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Along­side their mar­ket­place, Open­Sea’s API plat­form pow­ers third-par­ty tool­ing, with their REST API serv­ing as the back­bone of a num­ber of large projects in the Web3 com­mu­ni­ty, such as MetaMask, Coinbase Wallet, and Rainbow, among others.

OpenSea's Dev Platform

Open­Sea’s de­vel­op­er tool­ing con­sists of a REST API that en­ables developers to access and display metadata about NFTs, and a Soft­ware De­vel­op­ment Kit (SDK) that builds on top of the API to en­able the de­vel­op­ment that directly interfaces with the blockchain, such as for the creation of NFT marketplaces via the buying & selling of digital assets. The Open­Sea dev plat­form pro­vides a num­ber of key val­ue-adds.

For the application development via the API: 

1. Straightforward process to showcase NFTs and collections on the frontend.
2. Ac­cess to metadata about transactions, ownership and other details for each asset and collection in OpenSea’s database.
3. The ability to monitor any user’s wallet for NFT transactions, and retrieve information about any user’s assets.
4. Robust data management tools, including filtration and statistics by category.
5. Open­Sea pro­vides com­pre­hen­sive doc­u­men­ta­tion that makes it easy to get started us­ing their API.

And for smart contract interaction via the SDK:

1. Ac­cess to the largest com­mu­ni­ty in the space for col­lec­tors & sell­ers via Open­Sea’s ex­change con­tract.
2. The ability to build e-commerce functionality that reads and writes to the blockchain without deploying your own contracts.
3. Build native marketplaces for the buying & selling of NFTs with a wide range of features and payment structures.
4. Open­Sea pro­vides built-in roy­al­ty sup­port through Roy­al­ty Reg­istry that is standard­ized across plat­forms.
5. The Open­Sea SDK doc­u­men­ta­tion is reg­u­lar­ly up­dat­ed for com­pli­ance with the lat­est So­lid­i­ty standards.

1. API Tooling

The Open­Sea API pro­vides end­points for the fol­low­ing in­dexed mod­els on the Open­Sea plat­form: as­sets (in­di­vid­ual ERC-721/ERC-1155 to­kens), NFT col­lec­tions, events, or­ders, accounts, and as­set con­tracts. As part of the SDK func­tion­al­i­ty, the or­ders API al­lows for re­trieval (GET) and sub­mis­sion (POST) of NFT or­ders. Open­Sea pro­vides ac­cess to both Main­net & Test­net (via the Ethereum Rinkeby network) APIs so de­vel­op­ers can build and test with­out spend­ing real mon­ey.  

Some API end­points (orders & events) are gat­ed by Open­Sea to pre­vent mis­use. To build with these end­points, you can re­quest an API key here. 

Now, we’ll ex­plore Open­Sea’s API mod­els more close­ly, and dis­cuss the scope and func­tion of each. Pop­u­lar end­points & API calls are also pro­vid­ed be­low.

1. Contracts
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   A con­tract is a de­ployed smart con­tract on the Ethereum net­work. It is as­so­ci­at­ed with a sin­gle own­er ac­count. Contracts are automatically executed when predetermined terms and conditions are met—in OpenSea’s case, they exist between the buyers and seller of an NFT collection, and are used to execute trades.
2. Assets
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   As­sets rep­re­sent in­di­vid­ual to­kens emerg­ing from a con­tract. They can be owned by one or more ac­counts, and con­tain meta­da­ta about each asset. This data includes information about the asset’s ID, owner, name, and the contract it is contained within, as well as me­dia (the image url that the asset represents) and creator-defined traits. As­sets are how Open­Sea refers to NFTs.
3. Orders
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   An or­der is an ac­count-sub­mit­ted in­tent to buy/sell an as­set. It ex­ists off-chain, and has a type: bid or ask. It also con­tains meta­da­ta that is re­quired to match to NFTs on-chain. There are two par­tic­i­pants in an or­der: a mak­er, who makes liq­uidi­ty and acts as a first mover in a sale by declaring intent to sell or buy/bid on an item, and a tak­er, who takes liq­uid­i­ty and acts as the sec­ond mover in a sale by buying or accepting a bid on the item. Orders can be bundled within a specific collection.
   
4. Events
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   An event rep­re­sents a state-change on an as­set. There are on-chain events like trans­fers, sales, and mints, as well as off-chain events like bids and list­ings. Events can be private.
5. Accounts
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   Ac­counts rep­re­sent users on the Open­Sea mar­ket­place via their wal­let ad­dress­es and as­so­ci­at­ed user­names. They can own one or more as­sets, and act as makers or tak­ers in an or­der.
6. Collections
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   A col­lec­tion is a group­ing of the as­sets in one or more con­tract. They con­tain meta­da­ta such as roy­al­ty in­for­ma­tion and so­cial links, and they have one or more au­tho­rized ed­i­tors. Col­lec­tions ex­ist en­tire­ly off-chain. They are associated with metadata such as creator royalties and descriptions. Some pop­u­lar NFT col­lections in­clude Bored Ape Yacht Club, Cryp­to­P­unks, and Cryp­to Coven.
   

Some popular end­points & API calls in­clude:

• Get/ Assets
  • Fetch­es a list of to­kens based on fil­ter­ing cri­te­ria (such as as­set_­con­trac­t_address or col­lec­tion_s­lug)
  
• GET /as­set/:con­trac­t_ad­dress/:to­ken_id
  • Fetch­es de­tailed in­for­ma­tion about a spe­cif­ic to­ken, in­clud­ing a list of own­ers for ERC-1155 to­kens and all open or­ders on a to­ken.
• GET /col­lec­tions
  • Fetch­es a list of col­lec­tions. Also sup­ports fil­ter­ing op­tions, such as as­set_own­er.
• GET /col­lec­tions/:slug/stats 
  • Fetch­es sta­tis­ti­cal in­for­ma­tion about a spe­cif­ic col­lec­tion, in­clud­ing an up-to-date floor price.
• GET /events
  • Fetch­es a list of events based on fil­ters.
  • Re­quires an API key head­er (X-API-KEY: {KEY}).
• GET /or­ders
  • Fetch­es a list of or­ders. Can be mod­i­fied with fil­ter­ing op­tions like or­der type or with a spe­cif­ic mak­er or tak­er.

You can find a complete list of the Open­Sea API calls & end­points here. 

2. SDK Tooling

Open­Sea’s SDK tool­ing is an npm pack­age avail­able for web de­vel­op­ers look­ing to build ecom­merce func­tion­al­i­ty into their ap­plications. Through the SDK Java­Script li­brary, you can build na­tive mar­ket­places for the buy­ing & sell­ing of NFTs with no need to de­ploy smart contracts or back­end or­der­books.  

Open­Sea’s SDK is backed by the REST API we ex­plored above, and em­ploys Web3.js (a popu­lar pack­age for EVM in­ter­ac­tions) to pow­er in­ter­ac­tions with the blockchain for the creation and fulfillment of NFT orders.

The SDK sup­ports func­tion­al­i­ty like fetch­ing as­sets, mak­ing of­fers, mak­ing list­ings & sell­ing items, run­ning crowd­sales, fetch­ing or­ders, buy­ing items, ac­cept­ing of­fers, and trans­fer­ring items or coins (gift­ing). 

It also of­fers an ad­vanced set of fea­tures that in­cludes the abil­i­ty to sched­ule fu­ture list­ings, pur­chase items for oth­er users, make bulk trans­fers of NFTs, cre­ate bun­dles of NFTs, use ERC-20 to­kens as pay­ment in­stead of Ether, cre­ate pri­vate auc­tions, share sale fees with Open­Sea, and lis­ten to events. 

It is easy to set up (via npm in­stall) and is in­te­grat­ed na­tive­ly with Open­Sea’s ex­change to di­rect­ly cre­ate and ful­fill buy/sell or­ders. 

You can in­stall and ex­plore the func­tion­al­i­ty of Open­Sea’s Java­Script SDK li­brary here.
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