https://github.com/fastapi/typer

Typer, build great CLIs. Easy to code. Based on Python type hints.
https://github.com/fastapi/typer

cli click python python3 shell terminal typehints typer

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

Host: GitHub
URL: https://github.com/fastapi/typer
Owner: fastapi
License: mit
Created: 2019-12-24T12:24:11.000Z (almost 6 years ago)
Default Branch: master
Last Pushed: 2025-05-02T10:51:49.000Z (7 months ago)
Last Synced: 2025-05-05T15:18:05.373Z (7 months ago)
Topics: cli, click, python, python3, shell, terminal, typehints, typer
Language: Python
Homepage: https://typer.tiangolo.com/
Size: 1.61 MB
Stars: 16,950
Watchers: 80
Forks: 725
Open Issues: 179
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE
- Citation: CITATION.cff
- Security: SECURITY.md

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README

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.

## FastAPI of CLIs

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

## Installation

Create and activate a virtual environment and then install **Typer**:

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

## Example

### The absolute minimum

* Create a file `main.py` with:

```Python
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:

```console
// 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.

## Use Typer in your code

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

```Python
import typer

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

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

Now you could run it with Python directly:

```console
// 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

// 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.

## 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:

```console
$ 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:

```console
$ 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:

```console
$ 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:

```console
// 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.
```

### 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`:

```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 the `typer` command.

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

## Dependencies

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

By default it also comes with extra standard dependencies:

* rich: to show nicely formatted errors automatically.
* shellingham: to 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`.

### `typer-slim`

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

When you install with:

```bash
pip install typer
```

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

```bash
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.

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