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

Documentation: https://typer.tiangolo.com

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

Typer is a library for building CLI applications that users will love using and developers will love creating. Based on Python 3.6+ type hints.

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.

FastAPI of CLIs

Typer is FastAPI's little sibling.

And it's intended to be the FastAPI of CLIs.

Requirements

Python 3.6+

Typer stands on the shoulders of a giant. Its only internal dependency is Click.

Installation

Note: that will include Rich. Rich is the recommended library to display information on the terminal, it is optional, but when installed, it's deeply integrated into Typer to display beautiful output.

Example

The absolute minimum

• Create a file main.py with:

```Python import typer

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

if name == "main": typer.run(main) ```

Run it

Run your application:

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

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.

```Python hl_lines="3 6 11 20" 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).

Run the upgraded example

Check the new help:

Now check the help for the hello command:

And now check the help for the goodbye command:

Now you can try out the new command line application:

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 3.6+.

For example, for an int:

Python total: int

or for a bool flag:

Python 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 Typer CLI.

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

Optional Dependencies

Typer uses Click internally. That's the only dependency.

But you can also install extras:

• rich: and Typer will show nicely formatted errors automatically.
• shellingham: and Typer will automatically detect the current shell when installing completion.
  • With shellingham you can just use --install-completion.
  • Without shellingham, you have to pass the name of the shell to install completion for, e.g. --install-completion bash.

You can install typer with rich and shellingham with pip install typer[all].

License

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