diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..4907a28
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+.venv/
+__pycache__/
+.pytest_cache/
+*.py[cod]
+config.yaml
+instance/
diff --git a/README.md b/README.md
index c82740d..1e1c208 100644
--- a/README.md
+++ b/README.md
@@ -10,9 +10,13 @@ Amounts and worked/vacation/sick statuses selected for dates are stored persiste
 python3 -m venv .venv
 source .venv/bin/activate
 pip install -r requirements.txt
-python app.py
+waitress-serve --host=0.0.0.0 --port=9009 app:app
 ```
 
+To use a different port, substitute it in the command (for example,
+`--port=8080`). The application exposes its WSGI callable as `app:app`, so it
+can also be used by platforms that ask for an application entry point.
+
 Set the username, password, and Flask signing key in `config.yaml` before starting. This file is excluded from Git. Use `config.example.yaml` as the documented template when setting up another machine.
 
 The two paid quick-choice buttons are configured in the same file:
@@ -36,6 +40,8 @@ python scripts/import_excel.py /path/to/fatima.xlsx
 
 Add `--apply` to import. The command backs up the existing SQLite file before updating it.
 
-On the iPhone, visit `http://<your-computer-on-the-local-network>:5000`. The development server listens on all network interfaces. For anything exposed beyond a trusted home network, run behind HTTPS with a production WSGI server.
+On the iPhone, visit `http://<your-computer-on-the-local-network>:9009`.
+Waitress listens on all network interfaces with the command above. For anything
+exposed beyond a trusted home network, put it behind an HTTPS reverse proxy.
 
 For deployments, `APP_CONFIG` can point to a YAML file elsewhere. `SECRET_KEY`, `APP_USERNAME`, and `APP_PASSWORD` environment variables optionally override the corresponding YAML values.
diff --git a/app.py b/app.py
index 8201e34..eaaaee4 100644
--- a/app.py
+++ b/app.py
@@ -273,4 +273,4 @@ def create_app(test_config=None):
 app = create_app()
 
 if __name__ == "__main__":
-    app.run(host="0.0.0.0", port=int(os.environ.get("PORT", "9009")), debug=True)
+    app.run(host="0.0.0.0", port=int(os.environ.get("PORT", "9009")))
diff --git a/requirements.txt b/requirements.txt
index 29ed046..4a04aaf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 Flask==3.1.1
 PyYAML==6.0.2
 openpyxl==3.1.5
+waitress==3.0.2