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Typer, build great CLIs. Easy to code. Based on Python type hints.

Documentation: https://typer.tiangolo.com

Source Code: https://github.com/fastapi/typer

Typer is a library for building CLI applications that users will love using and developers will love creating. Based on Python type hints.

It's also a command line tool to run scripts, automatically converting them to CLI applications.

The key features are:

• Intuitive to write: Great editor support. Completion everywhere. Less time debugging. Designed to be easy to use and learn. Less time reading docs.
• Easy to use: It's easy to use for the final users. Automatic help, and automatic completion for all shells.
• Short: Minimize code duplication. Multiple features from each parameter declaration. Fewer bugs.
• Start simple: The simplest example adds only 2 lines of code to your app: 1 import, 1 function call.
• Grow large: Grow in complexity as much as you want, create arbitrarily complex trees of commands and groups of subcommands, with options and arguments.
• Run scripts: Typer includes a typer command/program that you can use to run scripts, automatically converting them to CLIs, even if they don't use Typer internally.

Help us define Typer's future by filling the Typer developer survey. ✨

Typer is FastAPI's little sibling, it's the FastAPI of CLIs.

Create and activate a virtual environment and then install Typer:

$ pip install typer
---> 100%
Successfully installed typer rich shellingham

• Create a file main.py with:

def main(name: str):
    print(f"Hello {name}")

This script doesn't even use Typer internally. But you can use the typer command to run it as a CLI application.

Run your application with the typer command:

// Run your application
$ typer main.py run

// You get a nice error, you are missing NAME
Usage: typer [PATH_OR_MODULE] run [OPTIONS] NAME
Try 'typer [PATH_OR_MODULE] run --help' for help.
╭─ Error ───────────────────────────────────────────╮
│ Missing argument 'NAME'.                          │
╰───────────────────────────────────────────────────╯


// You get a --help for free
$ typer main.py run --help

Usage: typer [PATH_OR_MODULE] run [OPTIONS] NAME

Run the provided Typer app.

╭─ Arguments ───────────────────────────────────────╮
│ *    name      TEXT  [default: None] [required]   |
╰───────────────────────────────────────────────────╯
╭─ Options ─────────────────────────────────────────╮
│ --help          Show this message and exit.       │
╰───────────────────────────────────────────────────╯

// Now pass the NAME argument
$ typer main.py run Camila

Hello Camila

// It works! 🎉

This is the simplest use case, not even using Typer internally, but it can already be quite useful for simple scripts.

Note: auto-completion works when you create a Python package and run it with --install-completion or when you use the typer command.

Now let's start using Typer in your own code, update main.py with:

import typer


def main(name: str):
    print(f"Hello {name}")


if __name__ == "__main__":
    typer.run(main)

Now you could run it with Python directly:

// Run your application
$ python main.py

// You get a nice error, you are missing NAME
Usage: main.py [OPTIONS] NAME
Try 'main.py --help' for help.
╭─ Error ───────────────────────────────────────────╮
│ Missing argument 'NAME'.                          │
╰───────────────────────────────────────────────────╯


// You get a --help for free
$ python main.py --help

Usage: main.py [OPTIONS] NAME

╭─ Arguments ───────────────────────────────────────╮
│ *    name      TEXT  [default: None] [required]   |
╰───────────────────────────────────────────────────╯
╭─ Options ─────────────────────────────────────────╮
│ --help          Show this message and exit.       │
╰───────────────────────────────────────────────────╯

// Now pass the NAME argument
$ python main.py Camila

Hello Camila

// It works! 🎉

Note: you can also call this same script with the typer command, but you don't need to.

This was the simplest example possible.

Now let's see one a bit more complex.

Modify the file main.py.

Create a typer.Typer() app, and create two subcommands with their parameters.

import typer

app = typer.Typer()


@app.command()
def hello(name: str):
    print(f"Hello {name}")


@app.command()
def goodbye(name: str, formal: bool = False):
    if formal:
        print(f"Goodbye Ms. {name}. Have a good day.")
    else:
        print(f"Bye {name}!")


if __name__ == "__main__":
    app()

And that will:

• Explicitly create a typer.Typer app.
  • The previous typer.run actually creates one implicitly for you.
• Add two subcommands with @app.command().
• Execute the app() itself, as if it was a function (instead of typer.run).

Check the new help:

$ python main.py --help

 Usage: main.py [OPTIONS] COMMAND [ARGS]...

╭─ Options ─────────────────────────────────────────╮
│ --install-completion          Install completion  │
│                               for the current     │
│                               shell.              │
│ --show-completion             Show completion for │
│                               the current shell,  │
│                               to copy it or       │
│                               customize the       │
│                               installation.       │
│ --help                        Show this message   │
│                               and exit.           │
╰───────────────────────────────────────────────────╯
╭─ Commands ────────────────────────────────────────╮
│ goodbye                                           │
│ hello                                             │
╰───────────────────────────────────────────────────╯

// When you create a package you get ✨ auto-completion ✨ for free, installed with --install-completion

// You have 2 subcommands (the 2 functions): goodbye and hello

Now check the help for the hello command:

$ python main.py hello --help

 Usage: main.py hello [OPTIONS] NAME

╭─ Arguments ───────────────────────────────────────╮
│ *    name      TEXT  [default: None] [required]   │
╰───────────────────────────────────────────────────╯
╭─ Options ─────────────────────────────────────────╮
│ --help          Show this message and exit.       │
╰───────────────────────────────────────────────────╯

And now check the help for the goodbye command:

$ python main.py goodbye --help

 Usage: main.py goodbye [OPTIONS] NAME

╭─ Arguments ───────────────────────────────────────╮
│ *    name      TEXT  [default: None] [required]   │
╰───────────────────────────────────────────────────╯
╭─ Options ─────────────────────────────────────────╮
│ --formal    --no-formal      [default: no-formal] │
│ --help                       Show this message    │
│                              and exit.            │
╰───────────────────────────────────────────────────╯

// Automatic --formal and --no-formal for the bool option 🎉

Now you can try out the new command line application:

// Use it with the hello command

$ python main.py hello Camila

Hello Camila

// And with the goodbye command

$ python main.py goodbye Camila

Bye Camila!

// And with --formal

$ python main.py goodbye --formal Camila

Goodbye Ms. Camila. Have a good day.

Note: If your app only has one command, by default the command name is omitted in usage: python main.py Camila. However, when there are multiple commands, you must explicitly include the command name: python main.py hello Camila. See One or Multiple Commands for more details.

In summary, you declare once the types of parameters (CLI arguments and CLI options) as function parameters.

You do that with standard modern Python types.

You don't have to learn a new syntax, the methods or classes of a specific library, etc.

Just standard Python.

For example, for an int:

total: int

or for a bool flag:

force: bool

And similarly for files, paths, enums (choices), etc. And there are tools to create groups of subcommands, add metadata, extra validation, etc.

You get: great editor support, including completion and type checks everywhere.

Your users get: automatic --help, auto-completion in their terminal (Bash, Zsh, Fish, PowerShell) when they install your package or when using the typer command.

For a more complete example including more features, see the Tutorial - User Guide.

Typer stands on the shoulders of giants. It has three required dependencies:

• Click: a popular tool for building CLIs in Python. Typer is based on it.
• rich: to show nicely formatted errors automatically.
• shellingham: to automatically detect the current shell when installing completion.

There used to be a slimmed-down version of Typer called typer-slim, which didn't include the dependencies rich and shellingham, nor the typer command.

However, since version 0.22.0, we have stopped supporting this, and typer-slim now simply installs (all of) Typer.

If you want to disable Rich globally, you can set an environmental variable TYPER_USE_RICH to False or 0.

This project is licensed under the terms of the MIT license.