> For the complete documentation index, see [llms.txt](https://docs.fractalbitcoin.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fractalbitcoin.io/articles/alkanes-on-bitcoin-fueling-smart-contracts-on-bitcoin-natively.md). # Alkanes on Bitcoin: Fueling Smart Contracts on Bitcoin Natively Bitcoin is programmable. Not someday — today. Thanks to Alkanes, developers can now build more expressive apps on Bitcoin. It’s simple, powerful, and 100% Bitcoin-native. ### 1. What are Alkanes? **What is Alkanes?** Alkanes is a smart contract system built natively on Bitcoin. Think of it like Ethereum-style smart contracts — but without leaving the Bitcoin chain. It allows developers to create and deploy decentralized applications (dApps) using Bitcoin’s native security and transaction system. At the core of Alkanes: * Contracts are written in **Rust** and compiled to **WebAssembly (WASM)**. * They’re deployed **onchain** using Bitcoin’s witness data (like Ordinals inscriptions). * They run through **Protorunes**, a messaging protocol encoded in Bitcoin transactions using OP\_RETURN. * All data and executions are indexed by **Metashrew**, an open-source stack purpose-built for Bitcoin smart contracts. ### How Do Alkanes Smart Contracts Work? Alkanes contracts are self-contained programs that operate natively on Bitcoin. Each contract can: * Store persistent **state** (e.g., balances, logic conditions) * Execute functions based on **opcodes** (numeric instructions) * Accept inputs via **cellpacks** (formatted data packets) * Handle **both** BTC and Alkanes-native tokens These contracts are triggered using **Protorunes** — messages embedded in Bitcoin transactions that tell contracts what to do, such as updating a balance or triggering a lending action. Want to query a contract without changing state? Alkanes supports **off-chain simulations**, making it easy to fetch data or test logic before pushing to the blockchain. ### Why Alkanes is Fuel for Bitcoin Programmability Here’s what sets Alkanes apart in the Bitcoin ecosystem: **1. Native UTXO Integration** Alkanes works directly with Bitcoin’s UTXO model, unlocking new ways to move, manage, and program BTC. **2. Modular and Composable** Contracts can interact with one another, enabling complex dApps built from smaller, reusable parts — like DeFi legos, but on Bitcoin. **3. Developer-Friendly** Rust and WebAssembly are already familiar to many Web3 devs. If you’ve built on Ethereum or Polkadot, you’ll feel right at home. **4. Transparent and Indexable** Every contract and execution is tracked and searchable via Metashrew, ensuring full auditability and trust. ### Conclusion Alkanes transform Bitcoin from a static, value-holding asset into a fully programmable platform — without compromising Bitcoin’s core values of decentralization, transparency, and security. With Alkanes, Bitcoin isn’t just digital gold — it’s programmable fuel. \ More details: