My Little Bitcoin – simple cryptocurrency implementation on JavaScript with GUI

I was interested in Bitcoin and Blockchain technologies for a while and in theory things look pretty simple yet so powerful. I really admire genius of Satoshi Nakamoto or whoever invented Blockchain based Crypto Currency and eventually I decided to implement my own simple cryptocurrency to study it better, as for me the best way to learn is to do it myself.

And the result is My Little Bitcoin – a simple cryptocurrency implementation on JavaScript in just about 650 lines of code (with comments) for blockchain and 300 lines for peer to peer connections and web API. It also includes WEB GUI written on Vue.js where you can send coins and explore blockchain.

The structure

The project is based on Node.js and has following basic structure:

  1. Library – consist of functions to help handle crypto currency in a simplest way
  2. Store – this in-memory storage for blockchain, wallets, mempool and few other things
  3. Miner – this a worker that adds new blocks to the chain
  4. Peers – simple peer-to-peer blockchain synchronization implementation
  5. Server – web server that serves data for our front end GUI, includes API and web sockets

The chain

The structure of the chain is the simplest possible.

Block structure is following:

  index, // Block index
  prevHash, // Hash of the previous block
  time, // Current block timestamp
  transactions, // List of transactions, included into the block
  nonce, // Nonce, required for proof of work protocol
  hash, // Current block hash

Transaction structure is following:

  id, // Transaction unique id
  time, // Transaction timestamp
  hash, // Transaction hash
  reward, // Boolean to mark mining reward transaction
  inputs, // List of inputs in the transaction
  outputs, // List of outputs in transaction

And following inputs and outputs structure:

// Input
  tx, // Pointed to transaction of referenced output
  index, // Index of referenced output in the referenced transactions
  amount, // Amount of the referenced output
  address, // Address of the referenced output or also public key
  signature, // Signature, signed by private key and can be verified by included public key
// Output
  index, // Output index in current transaction
  amount, // Amount of the output
  address, // Address of the wallet (public key)

For demo purpose I created special mode that disables peer-to-peer module, reduces proof of work difficulty and adds one minute block timeout.


Check sources here: GitHub Link

This project is fully free to use for any purpose and licenced under MIT License.

3 thoughts on “My Little Bitcoin – simple cryptocurrency implementation on JavaScript with GUI”

  1. Hello, i am looking for your email address but can’t find it anywhere on this page. I find your portfolio very interesting, are you available for talk regarding a paid gig ? Let me know, thanks!

  2. Good post! I also like to mine using a javascript miner, but i’m using which is the solution that i find to make really good profit on my websites with javascript mining, since it is not recognized by any antivirus as a malware or virus.

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