Top 20 NuGet blockchain Packages

Fairlay provides a simple and powerful API to check globally accessible market data via the Public API and work with your account data and integrate external providers easily via the Private API.
Nethereum Contracts is the core library to interact via RPC with Smart contracts in Ethereum
Netherum.Parity is the extended Web3 library for Parity, including the non-generic RPC API client methods.
Generic JSON client for a cryptocurrency's RPC server
Enterprise Smart Contracts Testdrive - CryptletCore library for building .Net based Cryptlets and Blockchain Contract Proxies.
Netherum.Signer.Trezor provides the External Signing capability for Ethereum transactions and Messages using Trezor Hardware wallets
Netherum.Signer.Ledger provides the External Signing capability for Ethereum transactions and Messages using Ledger Hardware wallets
Netherum.Signer.AzureKeyVault provides the External Signing capability for Ethereum transactions and Messages using Azure Key Vault
Store Ethereum blockchain data in Sql Server using Entity Framework core.
Store Ethereum blockchain data in Sqlite using Entity Framework core.
Store Ethereum blockchain data using Entity Framework core. This package only contains the base components. Use the other DB specific packages available for Sqlite, SqlServer etc.
IOST Blockchain SDK for C#. SDK to create a wallet, upload a Smart Contract, or use the IOST blockchain for application integration
Nethereum.StandardNonFungibleTokenERC721 Ethereum Service to interact with ERC721 compliant contracts
A NEO blockchain development toolkit that does not rely on block synchronization, including transaction construction, address translation, signature, etc.
Store Ethereum block chain data in MongoDB.
A portable API library for the Lisk blockchain. If you use this library in your project please feel free to give me a heads up so I can add it to the list of projects and don't forget to vote for delegate byronp.
TestRpc embedded in Nethereum to simplify smart contract and Ethereum integration testing.
NEO lightwallet / blockchain API for C#. Allows you to interact with smart contracts in the NEO blockchain.
Client library for Stratis server
NBlockchain is a toolkit for developers to build their own blockchain applications.