When it comes to the rise of crypto collectables, it’s no surprise that many secondary markets have arisen for the exchange of these unique assets.

For those unfamiliar with non-fungible tokens (better known as NFTs), they are tokens which are unique from one another due to special characteristics or identifiers which distinguish them from others in a similar set.

Specifically within DeFi, we’ve seen NFTs play a role in the tokenization of assets and contracts alike, all of which play a larger role in the notion of composability – or different products interacting with one another towards a larger ecosystem.

In this overview, we’ll dive into OpenSea – an industry-leading decentralized exchange (DEX) for NFTs built on Ethereum.

What is OpenSea?

OpenSea is an open-sourced crypto collectible marketplace which allows users to trade popular tokens built on interoperable standards like ERC721.

Prior to OpenSea, there was no easy way to trade crypto collectables other than brokering over-the-counter (OTC) deals – a situation which invokes a large amount of trust and counterparty risk.

With OpenSea, users can bid directly for items owned by other users, with assets being exchanged instantaneously in the event the seller accepts a bid or a buyer accepts an offer.

While there are a number of other crypto collectible marketplaces on the market, OpenSea currently leads as the defacto choice for swapping NFTs.

Perhaps one of the more novel aspects is the “Rankings” feed which allows users to see which platforms and collectables are most in-demand at any given time.


OpenSea was founded in November of 2017 and is lead by Devin Finzer and Alex Atallah, both of which bring experience to a strong team with backgrounds from Stanford, UC Berkeley, Palantir, Google, Facebook, and Pinterest.

OpenSea has raised a little over $4M in funding, most recently with a $2.1M round lead by Animoca Brands, gumi Cryptos, Stanford StartX, and David Pazdan from MetaMask. Previous rounds were supported by YCombinator, Founders Fund, Coinbase Ventures, 1Confirmation, Blockstack, and Blockchain Capital.

How Does it Work?

To get started with OpenSea, simply connect a web3 wallet like MetaMask and over to the “Browse” tab.

The application automatically scans your wallet for any collectables you may have, along with the assets needed (like Ether) to purchase items off the marketplace.

When interacting with listed items, users will have the option to either enter an offer – assuming no price has been set by the seller – or accept the listed price similar to eBay’s “Buy it Now” feature.

When placing an offer, be sure to take note of what asset the offer is being placed in (ETH, DAI, etc.) as it can vary from item to item.

Once an offer has been placed, users will receive an email if their purchase is successful.

On the selling side of things, simply click Account in the top right then “My Items” and choose the item you wish to sell.

Here you will have the ability to select the price and duration of the sale along with the type of offering it is.

Listing is free, and upon the successful sale of items, OpenSea will take a 2.5% fee on the final sale price.

Get Involved

To stay up with all things OpenSea, we recommend following their official blog and Twitter.

To be active in the conversation, join the OpenSea Discord here.