Avalanche-CLI is a robust command-line tool designed to facilitate the development and testing of subnets in the Avalanche ecosystem. Primarily compatible with Linux and Mac, this tool enables developers to manage subnet creation, deployment, and customization with efficiency. It supports local and testnet (Fuji) deployments, provides integration with Ledger, and incorporates the Avalanche Package Manager for streamlined operations. Installation is straightforward, with binaries downloadable via a curl command, and customizable directory options are available. Developers can achieve rapid subnet prototyping using Dev Containers with GitHub Codespaces or local Docker setups. The CLI includes advanced features such as local network snapshots for state persistence and quick environment resets, customizable node configurations, and end-to-end test capabilities. With its capacity to deploy both locally and on cloud instances, alongside offering a detailed setup guide in its repository, Avalanche-CLI empowers developers to optimize blockchain innovation on Avalanche effectively.