Stellar

Stellar is an open-source, decentralized blockchain protocol for payments and issuing digital currencies. The network combines powerful features that make it simple to create, send and trade all forms of digital assets. It has no central authority and the network is verified by hundreds of nodes across the globe.

Networks Mainnet, Testnet
Released 2014
Consensus Federated Byzantine Agreement
Smart contracts No
Block time 3 - 5 seconds
Smart contract language(s) supported N/A
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The lumens requirement

Stellar relies on blockchain to keep the network in sync and has its own native token, called the lumen. It was created with a special purpose - to safeguard Stellar's ledger system. The platform requires each account holder to keep a few lumens at all times.