fast

Measure the current download speed

$ fast

$ fast [[-u|--upload]]

$ fast --single-line

fast [options]

-h, --help
    Displays help information about the command's usage, detailing available options and arguments.

-v, --version
    Displays the current version number of the fast-cli tool installed on the system.

-s, --single-stream
    Conducts the internet speed test using only a single connection stream, which can sometimes provide a more conservative or specific measurement in certain network conditions.

-u, --upload
    Initiates an upload speed test immediately after the download test has completed. By default, only the download speed is measured.

--json
    Outputs the speed test results in a structured JSON format, making it suitable for scripting, automation, and programmatic parsing of the data.

fast-cli is a command-line interface tool that allows users to check their internet download and optionally upload speed directly from the terminal. It leverages the fast.com API, which is provided by Netflix, to perform speed measurements. Unlike many native Linux commands, fast-cli is built on Node.js and distributed as an npm package, making it easily installable across various platforms including Linux, macOS, and Windows, provided Node.js and npm are installed. Its primary purpose is to offer a quick and straightforward way to assess network bandwidth without needing to open a web browser, providing a consistent experience to the web-based service.

The command 'fast' is not a standard, built-in Linux command. This analysis refers to 'fast-cli', a popular third-party tool distributed via Node.js's npm package manager. Therefore, it requires Node.js and npm to be installed on your system for its functionality. Its results are derived from the fast.com service and might differ from other speed test services (e.g., speedtest-cli) due to varying server locations, testing methodologies, or network routing.

Since fast-cli is an npm package, it needs to be installed globally on your system. Assuming Node.js and npm are already set up, you can install it using the following command:
npm install --global fast-cli

As an internet speed testing utility, fast-cli fundamentally requires an active and stable internet connection to perform its functions correctly and provide accurate network performance measurements. Without an internet connection, the command will not be able to reach the fast.com servers.

fast-cli was developed by Sindre Sorhus and a community of contributors as part of the vibrant Node.js ecosystem. It emerged from the desire to bring the simplicity and effectiveness of the fast.com web service—a Netflix-provided internet speed test—directly to the command line. Its development reflects a broader trend of porting web-based utilities to the terminal for enhanced convenience, automation, and a more streamlined user experience.

speedtest-cli, ping(8), wget(1), curl(1)