Alephium is the first operational sharded L1 blockchain scaling and enhancing PoW & UTXO concepts. Decentralization, self-sovereignty and security meet high-performance, accessibility and energy efficiency in a dev-friendly network optimized for DeFi & smart contract applications. From its technical design to its interfaces, Alephium has been created with usability and accessibility in mind. It's made to support powerful, scalable yet user-friendly decentralized applications and protocols. Blockflow: sharding on BTC’s proven foundations Alephium is built on the BlockFlow algorithm which delivers efficient and practical UTXO sharding. Inspired by distributed computing models, it combines DAG (Directed Acyclic Graph) and sharding. Being much more lightweight than other sharding methods, BlockFlow also natively supports single-step cross shard transactions, making the Alephium UX as smooth as any single chain platform. Proof of Less Work (PoLW) PoLW uses a clever combination of physical work and token economics to dynamically adjust the work required to mine new blocks, ensuring a reduced energy footprint compared to classic Nakamoto PoW mining. Smart contracts Alephium's smart contracts have been designed and implemented to be scalable, functional, practical with a focus on security and reduced state usage. Its stateful UTXO model combines the advantages of both the eUTXO model and the account model. Novel VM design Alephium uses a simple, safe and flexible virtual machine designed for dApps, and more specifically DeFi. Its dedicated VM leverages and improves on the UTXO model to address DeFi’s security issues and execution bottleneck. Our VM focuses on contract security and IO performance. The key features are its first-class token system, multiple-caller contract and fine-grained execution model. Some numbers - 16 shards running on mainnet. - 100MB RAM needed for a Raspberry-Pi based full node. - Over 3 years of Research & Development.