One of the biggest functional differences between QRL's two chains is smart contracts. QRL 2.0 has them; QRL Legacy does not. This guide explains what that means.
What a smart contract is
A smart contract is a program that lives on the blockchain and runs exactly as written, enforced by the network. Instead of "send 10 coins from A to B," a contract can encode arbitrary rules — a token, a marketplace, an escrow, a game — that move value when conditions are met. Once deployed, no one can quietly change it; the code is the rules.
QRL Legacy: no contracts, just fixed types
QRL Legacy deliberately keeps things simple. It supports only a fixed set of transaction types — transfers, the mining reward (coinbase), token operations, messages, and a slave-key feature — and nothing more. There's no virtual machine and no way to deploy custom programs.
This simplicity was a reasonable choice for a chain focused on being a secure, quantum-resistant store and transfer of value. But it means QRL Legacy can't host the contract-based applications people expect from a modern smart-contract chain.
QRL 2.0: EVM-compatible
QRL 2.0 changes that by being EVM-compatible. The Ethereum Virtual Machine (EVM) is the most widely-used smart-contract environment in the industry, and QRL 2.0's execution client (gqrl) runs the same kind of contract bytecode. In practice that means:
- contracts and developer tooling from the Ethereum world can largely be reused, and
- familiar standards apply — QRC-20 tokens and QRC-721 / QRC-1155 NFTs mirror Ethereum's ERC equivalents.
What stays distinctly QRL is the security layer: transactions are signed with quantum-resistant ML-DSA-87, and addresses are Q-prefixed and 41 characters, not Ethereum's 0x style.
Tokens and NFTs as contracts
A practical consequence: on QRL 2.0, tokens and NFTs are smart contracts, just like on Ethereum. A QRC-20 token is a contract that tracks balances; a QRC-721 NFT is a contract that tracks unique items. This explorer decodes those contracts so you can browse tokens, token transfers and NFTs directly. On QRL Legacy, by contrast, tokens are a built-in transaction type, not a contract.
Why it matters
Smart contracts are what let a chain host applications beyond simple payments — DeFi, NFTs, on-chain governance. By making QRL 2.0 EVM-compatible while keeping quantum-resistant signatures, the project aims to offer that programmability without giving up its core security premise.
Where to go next
- QRL Legacy vs QRL 2.0 — the full comparison.
- Gas and fees explained — what running a contract costs.
- Blocks and transactions — contract calls as transactions.