How to build an NFT marketplace likeOpenSea

There is a form of Blockchain smart contract standard that creates unique assets. The assets created by smart contracts are called tokens, and the assets created by this contract standard are called non-fungible tokens.

NFT, as an asset, has changed the whole game in many ways. Unlike any other assets in the market, if you create an NFT, you can set a seller's fee, which allows you to collect a percentage of the sale as revenue whenever the ownership of the NFT is changed. What's better is that as the owner, you can set the fee as high as you want.

Like any other marketplace, the NFT marketplace is simple. You, as a platform, will receive a commission whenever a transaction happens on your platform. For example, in the OpenSea marketplace, the commission is 2.5%.

seller import asset ⇒ seller list asset ⇒ buyer check asset ⇒ buyer bid asset ⇒ handle transaction

For buyers to list their NFTs on the marketplace, the platform should have a feature that allows sellers to import NFTs into the marketplace. The marketplace needs to know the NFT asset address to access the asset information for asset listing in the next step.

This feature is one of the most essential features. The sellers list assets to the platform for sale. Once buyers visit your marketplace, they will all the seller's listings. Such a feature will incentivize buyers to buy assets they find interesting.

Now the buyer finds something exciting and wants to purchase the asset. Therefore, the marketplace should have features that allow buyers to make offers to buy the asset or just purchase the asset with the asking price.

This is the most important part. Once both parties agree on a price, the marketplace will handle the transaction and take the commission.

Now that we know the features we should develop, it's time to discuss how to build it.

To handle transactions, we use solidity to write contracts that handle asset exchanges between 2 parties. Nowadays, many services allow you to deploy your contract quickly and cheaply. For example, you can choose a testnet to deploy the contract and pay the gas fee using the money from one of the faucets. So essentially, you can test your smart contract for free. OpenSea, for example, uses Wyvern Protocol to handle asset transactions.

You also need to build a backend to handle database read, write and execute smart contracts. Developing the product is a balancing act between your resources and the performance of the backend. Suppose you are a startup that has only a handful of engineers. In that case, you could simply use NodeJS as the programming language to build your backend by implementing Ethers.js or Hardhat. Your javascript engineer can easily build a prototype for you without learning a lot.

If you have a bigger budget, of course, you can choose Golang as your backend language.

The data flow from the database to your client may be schema heavy. GraphQL should be a good choice for your developer to quickly set up a scalable backend.

The role of the database is to record the contract address and account address. Therefore, we can simply use MongoDB as our database to have a flexible schema.

Choosing a framework like ReactJS, VueJS, and AngularJS should be a no-brainer for the frontend.

You can quickly find good engineers from the market, and also you can use the same framework to deploy your marketplace as an Android or IOS app or even a desktop app.

The choice of those frameworks only comes down to your CTO's preference and your engineers' skills.

This must be the question many ambitious entrepreneurs like you want to know. The development usually takes 4 to 6 months from scratch to deployment.

The development cost comes down to the features and functions you want for your marketplace. Usually, the cost is around $100,000.