Qtum

Qtum is a cryptocurrency platform that enables decentralized applications (dApps) and smart contracts to be developed and utilized. These dApps work on mobile devices, and is compatible with most major blockchain ecosystems. Smart contract creation on the Qtum platform can be done using several programming languages that are supported by Qtum's x86 Virtual Machine. The Qtum platform uses their own Decentralized Governance Protocol (DGP) that enables blockchain setting modification through the use of smart contracts.

Introduction to Qtum.

Qtum is a decentralized blockchain project built on Bitcoin's UTXO model, with support for Ethereum Virtual Machine based smart contracts, and secured by a proof of stake consensus model. It achieves this through the revolutionary Account Abstraction Layer which allows the EVM to communicate with Qtum's Bitcoin-like UTXO blockchain. For more general information about Qtum as well as links to join our community, go to https://qtum.org

Welcome to the Qtum Fastlane Main Network. This is the main network where the tokens hold value and should be guarded very carefully. If you are testing the network, or developing unstable software on Qtum, we highly recommend using either testnet or regtest mode.

The major features of the Qtum network include:

Compatibility with the Ethereum Virtual Machine, which allows for compatibility with most existing Solidity based smart contracts. No special solidity compiler is required to deploy your smart contract to Qtum.

A Proof of Stake consensus system which is optimized for Qtum's contract model. Any user can stake and help to secure the network. There is no voting, master nodes, or minimum amount required. There have been transactions as small as 2 Qtum that have created blocks in the past. Staking from smart contracts is under development.

The Decentralized Governance Protocol is completely implemented and functional, which allows certain network parameters to be modified without a fork or other network disruption. This currently controls parameters like block size, gas prices, etc.

Uses the UTXO transaction model and is compatible with Bitcoin, allowing for existing tooling and workflows to be used with Qtum. This allows for the infamous SPV protocol to be used which is ideal for light wallets on mobile phones and IoT devices.

Note: Qtum Core is considered beta software. We make no warranties or guarantees of its security or stability.

Qtum Documentation and Usage Resources

These are some resources that might be helpful in understanding Qtum.

Basic usage resources:

• User guide
• Qtum-Qt Wallet Tutorial
• Qtum staking tutorial
• Qtum tutorial on Raspberry Pi
• Running Qtum on Amazon AWS using Qtum AMI
• Encrypting and unlocking wallet
• Testnet guide
• Block explorer, Older explorer

Development resources:

Qtum Book - A Developer's Guide To QTUM

Qtum contract usage

Deploying a custom token to Qtum

QtumJS document

Smart contract ICO example

Early example faucet contract

General Info about Qtum:

• CIRCLERESEARCH Qtum Primer
• Qtum's PoS vs CASPER
• Technical article explaining Qtum's PoS model in depth
• Developer's Tools
• Smart contract deployment tool
• https://github.com/qtumproject/solar
• DApp JavaScript Library
• https://github.com/qtumproject/qtumjs
• A toolkit for building qtum light wallets
• https://github.com/qtumproject/qtumjs-wallet
• CORS qtumd RPC proxy for DApp
• https://github.com/qtumproject/qtumportal
• Docker images for running qtum services
• https://github.com/qtumproject/qtum-docker
• qtum.info API that powers the block explorer and the QTUM Web wallet
• https://github.com/qtumproject/qtuminfo-api#qtuminfo-api-documentation

What is Qtum Core?

Qtum Core is our primary mainnet wallet. It implements a full node and is capable of storing, validating, and distributing all history of the Qtum network. Qtum Core is considered the reference implementation for the Qtum network.

Qtum Core currently implements the following:

• Sending/Receiving QTUM coins
• Sending/Receiving QRC20 tokens on the Qtum network
• Staking and creating blocks for the Qtum network
• Creating and interacting with smart contracts
• Running a full node for distributing the blockchain to other users
• "Prune" mode, which minimizes disk usage
• Regtest mode, which enables developers to very quickly build their own private Qtum network for Dapp testing
• Testnet mode, using the public Qtum Testnet, with faucet available
• Compatibility with the Bitcoin Core set of RPC commands and APIs
• Full SegWit capability with p2sh-segwit (legacy) and bech32 (native) addresses

Alternative Wallets

Qtum Core uses a full node model, and thus requires downloading the entire blockchain. If you do not need the entire blockchain, and do not intend on developing smart contracts, it may be more ideal to use an alternative wallet such as one of our light wallets that can be synchronized in a matter of seconds.

Qtum Web Wallet

A browser wallet that supports the Ledger hardware wallet, offline cold wallet, restoration from mobile wallets, creation of QRC20 tokens and QRC1155 NFTs.

Web site https://qtumwallet.org

User documentation https://github.com/qtumproject/documents/tree/master/en/QTUM-WebWallet-usage

Qtum Electrum

A light wallet that supports the Ledger and Trezor hardware wallets and is based on the well-known Electrum wallet software.

Download: https://github.com/qtumproject/qtum-electrum/releases

iOS and Android Wallets

These wallets run on mobile devices and synchronize quickly.

Android Download: https://play.google.com/store/apps/details?id=org.qtum.newwallet

iOS Download: https://github.com/qtumproject/qtum-ios (open source, deprecated)

Qnekt Chrome Wallet

This light wallet runs in your Chrome browser as a browser extension, based on the popular MetaMask wallet.

Community Resources

Make sure to check out these resources as well for more information and to keep up to date with all the latest news about Qtum. At least 1 developer is always around, so if you're developing on Qtum and need help, we'd love to welcome you to our community.

@Qtum on Twitter https://twitter.com/qtum

Qtum blog https://blog.qtum.org/

Qtum Telegram Group https://t.me/qtumofficial, other languages available

Qtum Discord https://discordapp.com/invite/wRfmkQ9

/r/Qtum on Reddit https://www.reddit.com/r/Qtum/

Qtum.org https://qtum.org

Qtum on Facebook https://www.facebook.com/QtumOfficial/

Qtum Smart Contract Limitations

EVM smart contracts cannot receive coins from or send coins to any address type other than pay-to-pubkeyhash (starts with Q) addresses. This is due to a limitation in the EVM

Contracts are not allowed to create contracts with an initial endowment of coins. The contract must first be created, and then be sent coins in a separate transaction. Humans are also not allowed to create contracts with an initial endowment of coins.

Although all of the infrastructure is present, Qtum Core does not currently parse Solidity event data. You must parse this yourself using either searchlogs or -record-log-opcodes features.

It is not possible to send a contract coins without also executing the contract. This is also the case of Ethereum. This was promised in earlier discussions and technically does work, but due to lack of time for testing this feature was disabled.

In Qtum there can be multiple addresses used to create a proof-of-stake block. However, the EVM can only see the first output using the coinbase operation in Solidity (this address is also the one registered for the continuous staker rewards after 2000 blocks).