diff --git a/poetry.lock b/poetry.lock
index ac6d7b4..ad0d2cf 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -313,7 +313,7 @@ files = [
 name = "click"
 version = "8.1.6"
 description = "Composable command line interface toolkit"
-category = "dev"
+category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
@@ -449,6 +449,43 @@ pipfile-deprecated-finder = ["pip-shims (>=0.5.2)", "pipreqs", "requirementslib"
 plugins = ["setuptools"]
 requirements-deprecated-finder = ["pip-api", "pipreqs"]
 
+[[package]]
+name = "markdown-it-py"
+version = "3.0.0"
+description = "Python port of markdown-it. Markdown parsing, done right!"
+category = "main"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "markdown-it-py-3.0.0.tar.gz", hash = "sha256:e3f60a94fa066dc52ec76661e37c851cb232d92f9886b15cb560aaada2df8feb"},
+    {file = "markdown_it_py-3.0.0-py3-none-any.whl", hash = "sha256:355216845c60bd96232cd8d8c40e8f9765cc86f46880e43a8fd22dc1a1a8cab1"},
+]
+
+[package.dependencies]
+mdurl = ">=0.1,<1.0"
+
+[package.extras]
+benchmarking = ["psutil", "pytest", "pytest-benchmark"]
+code-style = ["pre-commit (>=3.0,<4.0)"]
+compare = ["commonmark (>=0.9,<1.0)", "markdown (>=3.4,<4.0)", "mistletoe (>=1.0,<2.0)", "mistune (>=2.0,<3.0)", "panflute (>=2.3,<3.0)"]
+linkify = ["linkify-it-py (>=1,<3)"]
+plugins = ["mdit-py-plugins"]
+profiling = ["gprof2dot"]
+rtd = ["jupyter_sphinx", "mdit-py-plugins", "myst-parser", "pyyaml", "sphinx", "sphinx-copybutton", "sphinx-design", "sphinx_book_theme"]
+testing = ["coverage", "pytest", "pytest-cov", "pytest-regressions"]
+
+[[package]]
+name = "mdurl"
+version = "0.1.2"
+description = "Markdown URL utilities"
+category = "main"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "mdurl-0.1.2-py3-none-any.whl", hash = "sha256:84008a41e51615a49fc9966191ff91509e3c40b939176e643fd50a5c2196b8f8"},
+    {file = "mdurl-0.1.2.tar.gz", hash = "sha256:bb413d29f5eea38f31dd4754dd7377d4465116fb207585f97bf925588687c1ba"},
+]
+
 [[package]]
 name = "multidict"
 version = "6.0.4"
@@ -665,6 +702,21 @@ files = [
 dev = ["pre-commit", "tox"]
 testing = ["pytest", "pytest-benchmark"]
 
+[[package]]
+name = "prompt-toolkit"
+version = "3.0.39"
+description = "Library for building powerful interactive command lines in Python"
+category = "main"
+optional = false
+python-versions = ">=3.7.0"
+files = [
+    {file = "prompt_toolkit-3.0.39-py3-none-any.whl", hash = "sha256:9dffbe1d8acf91e3de75f3b544e4842382fc06c6babe903ac9acb74dc6e08d88"},
+    {file = "prompt_toolkit-3.0.39.tar.gz", hash = "sha256:04505ade687dc26dc4284b1ad19a83be2f2afe83e7a828ace0c72f3a1df72aac"},
+]
+
+[package.dependencies]
+wcwidth = "*"
+
 [[package]]
 name = "pydantic"
 version = "2.1.1"
@@ -833,6 +885,21 @@ snowballstemmer = ">=2.2.0"
 [package.extras]
 toml = ["tomli (>=1.2.3)"]
 
+[[package]]
+name = "pygments"
+version = "2.16.1"
+description = "Pygments is a syntax highlighting package written in Python."
+category = "main"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "Pygments-2.16.1-py3-none-any.whl", hash = "sha256:13fc09fa63bc8d8671a6d247e1eb303c4b343eaee81d861f3404db2935653692"},
+    {file = "Pygments-2.16.1.tar.gz", hash = "sha256:1daff0494820c69bc8941e407aa20f577374ee88364ee10a98fdbe0aece96e29"},
+]
+
+[package.extras]
+plugins = ["importlib-metadata"]
+
 [[package]]
 name = "pytest"
 version = "7.4.0"
@@ -891,6 +958,25 @@ urllib3 = ">=1.21.1,<3"
 socks = ["PySocks (>=1.5.6,!=1.5.7)"]
 use-chardet-on-py3 = ["chardet (>=3.0.2,<6)"]
 
+[[package]]
+name = "rich"
+version = "13.5.2"
+description = "Render rich text, tables, progress bars, syntax highlighting, markdown and more to the terminal"
+category = "main"
+optional = false
+python-versions = ">=3.7.0"
+files = [
+    {file = "rich-13.5.2-py3-none-any.whl", hash = "sha256:146a90b3b6b47cac4a73c12866a499e9817426423f57c5a66949c086191a8808"},
+    {file = "rich-13.5.2.tar.gz", hash = "sha256:fb9d6c0a0f643c99eed3875b5377a184132ba9be4d61516a55273d3554d75a39"},
+]
+
+[package.dependencies]
+markdown-it-py = ">=2.2.0"
+pygments = ">=2.13.0,<3.0.0"
+
+[package.extras]
+jupyter = ["ipywidgets (>=7.5.1,<9)"]
+
 [[package]]
 name = "ruff"
 version = "0.0.284"
@@ -918,6 +1004,18 @@ files = [
     {file = "ruff-0.0.284.tar.gz", hash = "sha256:ebd3cc55cd499d326aac17a331deaea29bea206e01c08862f9b5c6e93d77a491"},
 ]
 
+[[package]]
+name = "shellingham"
+version = "1.5.3"
+description = "Tool to Detect Surrounding Shell"
+category = "main"
+optional = false
+python-versions = ">=3.7"
+files = [
+    {file = "shellingham-1.5.3-py2.py3-none-any.whl", hash = "sha256:419c6a164770c9c7cfcaeddfacb3d31ac7a8db0b0f3e9c1287679359734107e9"},
+    {file = "shellingham-1.5.3.tar.gz", hash = "sha256:cb4a6fec583535bc6da17b647dd2330cf7ef30239e05d547d99ae3705fd0f7f8"},
+]
+
 [[package]]
 name = "snowballstemmer"
 version = "2.2.0"
@@ -951,6 +1049,31 @@ notebook = ["ipywidgets (>=6)"]
 slack = ["slack-sdk"]
 telegram = ["requests"]
 
+[[package]]
+name = "typer"
+version = "0.9.0"
+description = "Typer, build great CLIs. Easy to code. Based on Python type hints."
+category = "main"
+optional = false
+python-versions = ">=3.6"
+files = [
+    {file = "typer-0.9.0-py3-none-any.whl", hash = "sha256:5d96d986a21493606a358cae4461bd8cdf83cbf33a5aa950ae629ca3b51467ee"},
+    {file = "typer-0.9.0.tar.gz", hash = "sha256:50922fd79aea2f4751a8e0408ff10d2662bd0c8bbfa84755a699f3bada2978b2"},
+]
+
+[package.dependencies]
+click = ">=7.1.1,<9.0.0"
+colorama = {version = ">=0.4.3,<0.5.0", optional = true, markers = "extra == \"all\""}
+rich = {version = ">=10.11.0,<14.0.0", optional = true, markers = "extra == \"all\""}
+shellingham = {version = ">=1.3.0,<2.0.0", optional = true, markers = "extra == \"all\""}
+typing-extensions = ">=3.7.4.3"
+
+[package.extras]
+all = ["colorama (>=0.4.3,<0.5.0)", "rich (>=10.11.0,<14.0.0)", "shellingham (>=1.3.0,<2.0.0)"]
+dev = ["autoflake (>=1.3.1,<2.0.0)", "flake8 (>=3.8.3,<4.0.0)", "pre-commit (>=2.17.0,<3.0.0)"]
+doc = ["cairosvg (>=2.5.2,<3.0.0)", "mdx-include (>=1.4.1,<2.0.0)", "mkdocs (>=1.1.2,<2.0.0)", "mkdocs-material (>=8.1.4,<9.0.0)", "pillow (>=9.3.0,<10.0.0)"]
+test = ["black (>=22.3.0,<23.0.0)", "coverage (>=6.2,<7.0)", "isort (>=5.0.6,<6.0.0)", "mypy (==0.910)", "pytest (>=4.4.0,<8.0.0)", "pytest-cov (>=2.10.0,<5.0.0)", "pytest-sugar (>=0.9.4,<0.10.0)", "pytest-xdist (>=1.32.0,<4.0.0)", "rich (>=10.11.0,<14.0.0)", "shellingham (>=1.3.0,<2.0.0)"]
+
 [[package]]
 name = "typing-extensions"
 version = "4.7.1"
@@ -981,6 +1104,18 @@ secure = ["certifi", "cryptography (>=1.9)", "idna (>=2.0.0)", "pyopenssl (>=17.
 socks = ["pysocks (>=1.5.6,!=1.5.7,<2.0)"]
 zstd = ["zstandard (>=0.18.0)"]
 
+[[package]]
+name = "wcwidth"
+version = "0.2.6"
+description = "Measures the displayed width of unicode strings in a terminal"
+category = "main"
+optional = false
+python-versions = "*"
+files = [
+    {file = "wcwidth-0.2.6-py2.py3-none-any.whl", hash = "sha256:795b138f6875577cd91bba52baf9e445cd5118fd32723b460e30a0af30ea230e"},
+    {file = "wcwidth-0.2.6.tar.gz", hash = "sha256:a5220780a404dbe3353789870978e472cfe477761f06ee55077256e509b156d0"},
+]
+
 [[package]]
 name = "yarl"
 version = "1.9.2"
@@ -1072,4 +1207,4 @@ multidict = ">=4.0"
 [metadata]
 lock-version = "2.0"
 python-versions = ">=3.11,<3.12"
-content-hash = "544019c132db9541be699bb3aac24f07cd85ee90773412b581f509e273f9df51"
+content-hash = "5b81fe2c2ca1756c2c446ab727fd30fd976ed7d8c82ffb8f7d3870c38755bce6"
diff --git a/pyproject.toml b/pyproject.toml
index 93fcb9b..2849184 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,6 +11,8 @@ python = ">=3.11,<3.12"
 openai = "^0.27.8"
 pydantic = "^2.1.1"
 pydantic-settings = "^2.0.2"
+typer = {extras = ["all"], version = "^0.9.0"}
+prompt-toolkit = "^3.0.39"
 
 [tool.poetry.group.test.dependencies]
 pytest = "^7.4.0"
@@ -20,6 +22,9 @@ ruff = "^0.0.284"
 mypy = "^1.5.0"
 pydocstyle = "^6.3.0"
 
+[tool.poetry.scripts]
+chat = "llm_chat.cli:app"
+
 [build-system]
 requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"
diff --git a/src/llm_chat/chat.py b/src/llm_chat/chat.py
index 3bc8c86..35cf640 100644
--- a/src/llm_chat/chat.py
+++ b/src/llm_chat/chat.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Protocol
 
 from openai import ChatCompletion
 from openai.openai_object import OpenAIObject
@@ -17,6 +17,13 @@ INITIAL_SYSTEM_MESSAGES = [
 ]
 
 
+class ChatProtocol(Protocol):
+    """Protocol for chat classes."""
+
+    def send_message(self, message: str) -> str:
+        """Send a message to the assistant."""
+
+
 class Chat:
     """Interface class for OpenAI's ChatGPT chat API.
 
@@ -68,3 +75,8 @@ class Chat:
         message = response["choices"][0]["message"]["content"]
         self.conversation.messages.append(Message(role=Role.ASSISTANT, content=message))
         return message
+
+
+def get_chat(settings: OpenAISettings | None = None) -> ChatProtocol:
+    """Get a chat object."""
+    return Chat(settings=settings)
diff --git a/src/llm_chat/cli.py b/src/llm_chat/cli.py
new file mode 100644
index 0000000..7d8cff1
--- /dev/null
+++ b/src/llm_chat/cli.py
@@ -0,0 +1,90 @@
+from typing import Annotated, Any, Optional
+
+import typer
+from prompt_toolkit import PromptSession
+from rich.console import Console
+from rich.markdown import Markdown
+
+from llm_chat.chat import get_chat
+from llm_chat.settings import DEFAULT_MODEL, DEFAULT_TEMPERATURE, Model, OpenAISettings
+
+app = typer.Typer()
+
+
+def prompt_continuation(width: int, *args: Any) -> str:
+    """Prompt continuation for multiline input."""
+    return "." * (width - 1) + " "
+
+
+def get_console() -> Console:
+    """Get a console."""
+    return Console()
+
+
+def get_session() -> PromptSession[Any]:
+    """Get a prompt session."""
+    return PromptSession()
+
+
+def read_user_input(session: PromptSession[Any]) -> str:
+    """Read user input.
+
+    The main purpose of this function is to enable the injection of user input during
+    tests, since trying to inject a fake PromptSession into the chat function led to
+    the test hanging.
+    """
+    prompt: str = session.prompt(
+        ">>> ", multiline=True, prompt_continuation=prompt_continuation
+    )
+    return prompt
+
+
+@app.command()
+def chat(
+    api_key: Annotated[
+        Optional[str],
+        typer.Option(
+            ...,
+            "--api-key",
+            "-k",
+            help=(
+                "API key. Will read from the environment variable OPENAI_API_KEY "
+                "if not provided."
+            ),
+        ),
+    ] = None,
+    model: Annotated[
+        Model,
+        typer.Option(..., "--model", "-m", help="Model to use.", show_choices=True),
+    ] = DEFAULT_MODEL,
+    temperature: Annotated[
+        float,
+        typer.Option(
+            ..., "--temperature", "-t", help="Model temperature (i.e. creativeness)."
+        ),
+    ] = DEFAULT_TEMPERATURE,
+) -> None:
+    """Start a chat session."""
+    # TODO: Add option to load context from file.
+    # TODO: Add option to provide context string as an argument.
+    if api_key is not None:
+        settings = OpenAISettings(api_key=api_key, model=model, temperature=temperature)
+    else:
+        settings = OpenAISettings(model=model, temperature=temperature)
+
+    current_chat = get_chat(settings)
+    console = get_console()
+    session = get_session()
+
+    finished = False
+
+    console.print(f"[bold green]Model:[/bold green] {settings.model}")
+    console.print(f"[bold green]Temperature:[/bold green] {settings.temperature}")
+
+    while not finished:
+        prompt = read_user_input(session)
+        if prompt.strip() == "/q":
+            finished = True
+        else:
+            response = current_chat.send_message(prompt.strip())
+            console.print(Markdown(response))
diff --git a/src/llm_chat/settings.py b/src/llm_chat/settings.py
index d01801a..f266183 100644
--- a/src/llm_chat/settings.py
+++ b/src/llm_chat/settings.py
@@ -10,12 +10,16 @@ class Model(StrEnum):
     GPT4 = "gpt-4"
 
 
+DEFAULT_MODEL = Model.GPT3
+DEFAULT_TEMPERATURE = 0.7
+
+
 class OpenAISettings(BaseSettings):
     """Settings for the LLM Chat application."""
 
     api_key: str = ""
-    model: Model = Model.GPT3
-    temperature: float = 0.7
+    model: Model = DEFAULT_MODEL
+    temperature: float = DEFAULT_TEMPERATURE
 
     model_config: SettingsConfigDict = SettingsConfigDict(  # type: ignore[misc]
         env_file=".env",
diff --git a/tests/test_cli.py b/tests/test_cli.py
new file mode 100644
index 0000000..a64b4fc
--- /dev/null
+++ b/tests/test_cli.py
@@ -0,0 +1,46 @@
+from io import StringIO
+from unittest.mock import MagicMock
+
+from pytest import MonkeyPatch
+from rich.console import Console
+from typer.testing import CliRunner
+
+import llm_chat
+from llm_chat.chat import ChatProtocol
+from llm_chat.cli import app
+from llm_chat.settings import OpenAISettings
+
+runner = CliRunner()
+
+
+class ChatFake:
+    """Fake chat class for testing."""
+
+    received_messages: list[str] = []
+
+    def send_message(self, message: str) -> str:
+        """Echo the received message."""
+        self.received_messages.append(message)
+        return message
+
+
+def test_chat(monkeypatch: MonkeyPatch) -> None:
+    chat_fake = ChatFake()
+    output = StringIO()
+    console = Console(file=output)
+
+    def mock_get_chat(_: OpenAISettings) -> ChatProtocol:
+        return chat_fake
+
+    def mock_get_console() -> Console:
+        return console
+
+    mock_read_user_input = MagicMock(side_effect=["Hello", "/q"])
+
+    monkeypatch.setattr(llm_chat.cli, "get_chat", mock_get_chat)
+    monkeypatch.setattr(llm_chat.cli, "get_console", mock_get_console)
+    monkeypatch.setattr(llm_chat.cli, "read_user_input", mock_read_user_input)
+
+    result = runner.invoke(app)
+    assert result.exit_code == 0
+    assert chat_fake.received_messages == ["Hello"]