All the current implementations of blockchains are tightly coupled with the larger context and problems they (e.g. Bitcoin or Ethereum) are trying to solve. This makes understanding blockchains a necessarily harder task, than it must be. Especially source-code-wisely. This project is an attempt to provide as concise and simple implementation of a blockchain as possible.

From Wikipedia : Blockchain is a distributed database that maintains a continuously-growing list of records called blocks secured from tampering and revision.

Check also this blog post for a more detailed overview of the key concepts

• HTTP interface to control the node
• Use Websockets to communicate with other nodes (P2P)
• Super simple "protocols" in P2P communication
• Data is not persisted in nodes
• Simple proof-of-work: for a block to be added to the blockchain a proof of work (number stored on the block's nonce field) must be generated. The block mining process iterates the nonce value until the block's hash has a specific number of preceding 0s (the number of 0s is defined by the difficulty var)

(set up two connected nodes and mine 1 block)

npm install
HTTP_PORT=3001 P2P_PORT=6001 npm start
HTTP_PORT=3002 P2P_PORT=6002 PEERS=ws://localhost:6001 npm start
curl -H "Content-type:application/json" --data '{"data" : "Some data to the first block"}' http://localhost:3001/mineBlock

(set up three connected nodes and mine a block)

docker-compose up
curl -H "Content-type:application/json" --data '{"data" : "Some data to the first block"}' http://localhost:3001/mineBlock

curl http://localhost:3001/blocks

curl -H "Content-type:application/json" --data '{"data" : "Some data to the first block"}' http://localhost:3001/mineBlock

curl -H "Content-type:application/json" --data '{"peer" : "ws://localhost:6001"}' http://localhost:3001/addPeer

curl http://localhost:3001/peers