RSK is an open source smart contract platform that is secured by the Bitcoin network. RSK is designed to add value and increase the functionality of the Bitcoin ecosystem by providing smart contracts that are compatible with the network's code and can be written in Solidity. RSK smart contracts are powered by the SmartBitcoin (RBTC) which is linked to Bitcoin. (1 RBTC=1 BTC)
RSK developed the RIF Token which is intended to enable users to access a range of DApps within their ecosystem. In September 2019, RSK purchased the Spanish social media platform Taringa with the goal of using the RIF token as an incentive to encourage users to share content.

ProximaX is developing a NEM-based platform with several on-chain and off-chain protocols. At its core, ProximaX is based on the NEM blockchain, and is designed to be an all-in-one platform for developing DApps. The platform has several parallel layers that are intended to provide decentralized storage, messaging, streaming, and content delivery services. The network is powered by the NEM-based XPX token. ProximaX intends on using a hybrid consensus mechanism for validating value transfers on these layers. Consensus will be driven with a combination of Proof-of-Importance (PoI), Proof-of-Storage (PoSt), and Proof-of-Bandwidth (PoB).

Ubiq is an Ethereum fork that aims to create a more stable smart contract platform for building DApps. Ubiq's protocol currently uses a Proof-of-Work (PoW) consensus mechanism, but will switch to Proof-of-Stake in 2019. The network is powered by the UBQ coin.
Ubiq's goal is to create a reliable and stable platform for developing DApps by modifying Ethereum's code base with important changes that will make it more secure and reduce instability. Consensus is based on their Flux Difficulty Algorithm, which is designed to constantly adjust the hash rate to protect against network attacks.