Several companies specialize in NFT marketplace development. Here are a few notable ones,

OpenSea: OpenSea is one of the largest and most well-known NFT marketplaces. While they primarily focus on hosting NFTs, they also provide tools and resources for developers to create their own NFT marketplaces.

Rarible: Rarible is another popular NFT marketplace that allows users to create, buy, sell, and collect digital items secured with blockchain technology. They offer an open marketplace where anyone can mint and trade NFTs.

SuperRare: SuperRare is a platform that focuses on digital art NFTs. They curate high-quality digital artworks and provide a marketplace for collectors and creators to buy, sell, and trade these unique pieces.

If you're looking to develop your own NFT marketplace, you might consider reaching a reputed company. I suggest Trioangle Technologies one of the NFT Marketplace development company. They can help you with everything from smart contract development to building a user-friendly interface.