While there isn't a universally agreed-upon ranking, some of the top contenders for private blockchain development companies in 2024 include Interexy, Suffescom Solutions, Markovate, Ropstam Solutions, and Peiko. These companies offer a range of services like smart contract development, building NFT platforms, and creating custom blockchains for businesses. They have experience working on various blockchain platforms like Ethereum, Hyperledger, and Solana.