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<p align="center"> <a href="https://typer.tiangolo.com"><img src="https://typer.tiangolo.com/img/logo-margin/logo-margin-vector.svg#only-light" alt="Typer"></a> </p> <p align="center"> <em>Typer, build great CLIs. Easy to code. Based on Python type hints.</em> </p> <p align="center"> <a href="https://github.com/fastapi/typer/actions?query=workflow%3ATest" target="_blank"> <img src="https://github.com/fastapi/typer/workflows/Test/badge.svg" alt="Test"> </a> <a href="https://github.com/fastapi/typer/actions?query=workflow%3APublish" target="_blank"> <img src="https://github.com/fastapi/typer/workflows/Publish/badge.svg" alt="Publish"> </a> <a href="https://coverage-badge.samuelcolvin.workers.dev/redirect/fastapi/typer" target="_blank"> <img src="https://coverage-badge.samuelcolvin.workers.dev/fastapi/typer.svg" alt="Coverage"> <a href="https://pypi.org/project/typer" target="_blank"> <img src="https://img.shields.io/pypi/v/typer?color=%2334D058&label=pypi%20package" alt="Package version"> </a> </p>

Documentation: <a href="https://typer.tiangolo.com" target="_blank">https://typer.tiangolo.com</a>

Source Code: <a href="https://github.com/fastapi/typer" target="_blank">https://github.com/fastapi/typer</a>


Typer is a library for building <abbr title="command line interface, programs executed from a terminal">CLI</abbr> 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:

FastAPI of CLIs

Typer is <a href="https://fastapi.tiangolo.com" class="external-link" target="_blank">FastAPI</a>'s little sibling, it's the FastAPI of CLIs.

Installation

Create and activate a <a href="https://typer.tiangolo.com/virtual-environments/" class="external-link" target="_blank">virtual environment</a> and then install Typer:

<div class="termy">
$ pip install typer
---> 100%
Successfully installed typer rich shellingham
</div>

Example

The absolute minimum

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 it

Run your application with the typer command:

<div class="termy">
// 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! 🎉
</div>

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.

Use Typer in your code

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:

<div class="termy">
// 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! 🎉
</div>

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

Example upgrade

This was the simplest example possible.

Now let's see one a bit more complex.

An example with two subcommands

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:

Run the upgraded example

Check the new help:

<div class="termy">
$ 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
</div>

Now check the help for the hello command:

<div class="termy">
$ python main.py hello --help

 Usage: main.py hello [OPTIONS] NAME

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

And now check the help for the goodbye command:

<div class="termy">
$ 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 🎉
</div>

Now you can try out the new command line application:

<div class="termy">
// 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.
</div>

Recap

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 <a href="https://typer.tiangolo.com/tutorial/">Tutorial - User Guide</a>.

Dependencies

Typer stands on the shoulders of a giant. Its only internal required dependency is <a href="https://click.palletsprojects.com/" class="external-link" target="_blank">Click</a>.

By default it also comes with extra standard dependencies:

typer-slim

If you don't want the extra standard optional dependencies, install typer-slim instead.

When you install with:

pip install typer

...it includes the same code and dependencies as:

pip install "typer-slim[standard]"

The standard extra dependencies are rich and shellingham.

Note: The typer command is only included in the typer package.

License

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