diff --git a/README.md b/README.md
index 1e1c208..7382145 100644
--- a/README.md
+++ b/README.md
@@ -10,11 +10,11 @@ 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
-waitress-serve --host=0.0.0.0 --port=9009 app:app
+waitress-serve --host=0.0.0.0 --port=9009 fatima: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
+`--port=8080`). The application exposes its WSGI callable as `fatima: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.
@@ -30,6 +30,20 @@ amounts:
 
 The €0 and custom-amount controls remain available automatically.
 
+## Reverse proxy path
+
+The app is served below `/fatima` by default. Configure the external path in
+`config.yaml`:
+
+```yaml
+flask:
+  url_prefix: "/fatima"
+```
+
+Set `URL_PREFIX` in the environment to override this value at deployment time.
+Use an empty value (`url_prefix: ""` or `URL_PREFIX=`) to serve from `/` instead.
+The reverse proxy must preserve the prefix when forwarding requests to Waitress.
+
 ## Import the Excel calendar
 
 Preview an import without changing the database:
@@ -40,7 +54,7 @@ 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>:9009`.
+On the iPhone, visit `http://<your-computer-on-the-local-network>:9009/fatima/`.
 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.
 
diff --git a/config.example.yaml b/config.example.yaml
index 0b1abd9..6b308a8 100644
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -1,6 +1,8 @@
 flask:
   # Generate with: python -c "import secrets; print(secrets.token_hex(32))"
   secret_key: "replace-with-a-long-random-value"
+  # External path used by the reverse proxy. Use "" to serve from the domain root.
+  url_prefix: "/fatima"
 
 auth:
   username: "your-username"
diff --git a/app.py b/flask_fatima.py
similarity index 87%
rename from app.py
rename to flask_fatima.py
index eaaaee4..bb6980e 100644
--- a/app.py
+++ b/flask_fatima.py
@@ -10,6 +10,34 @@ from flask import Flask, jsonify, redirect, render_template, request, session, u
 import yaml
 
 
+def normalize_url_prefix(value):
+    if not isinstance(value, str):
+        raise RuntimeError("flask.url_prefix must be a string")
+    value = value.strip()
+    if not value or value == "/":
+        return ""
+    return f"/{value.strip('/')}"
+
+
+class UrlPrefixMiddleware:
+    """Mount a WSGI application below a configurable URL prefix."""
+
+    def __init__(self, application, prefix):
+        self.application = application
+        self.prefix = prefix
+
+    def __call__(self, environ, start_response):
+        path = environ.get("PATH_INFO", "")
+        if self.prefix and path != self.prefix and not path.startswith(f"{self.prefix}/"):
+            start_response("404 Not Found", [("Content-Type", "text/plain; charset=utf-8")])
+            return [b"Not Found"]
+
+        if self.prefix:
+            environ["SCRIPT_NAME"] = f"{environ.get('SCRIPT_NAME', '')}{self.prefix}"
+            environ["PATH_INFO"] = path[len(self.prefix):] or "/"
+        return self.application(environ, start_response)
+
+
 def load_yaml_config(path):
     config_path = Path(path)
     if not config_path.is_file():
@@ -28,8 +56,12 @@ def load_yaml_config(path):
         "SECRET_KEY": flask_config.get("secret_key"),
         "APP_USERNAME": auth.get("username"),
         "APP_PASSWORD": auth.get("password"),
+        "URL_PREFIX": normalize_url_prefix(flask_config.get("url_prefix", "/fatima")),
     }
-    missing = [name for name, value in required.items() if not isinstance(value, str) or not value]
+    missing = [
+        name for name, value in required.items()
+        if name != "URL_PREFIX" and (not isinstance(value, str) or not value)
+    ]
     if missing:
         raise RuntimeError(f"Missing or empty values in {config_path}: {', '.join(missing)}")
     presets = amount_config.get("presets", ["55", "27.50"])
@@ -58,8 +90,12 @@ def create_app(test_config=None):
     for name in ("SECRET_KEY", "APP_USERNAME", "APP_PASSWORD"):
         if os.environ.get(name):
             app.config[name] = os.environ[name]
+    if "URL_PREFIX" in os.environ:
+        app.config["URL_PREFIX"] = normalize_url_prefix(os.environ["URL_PREFIX"])
     if test_config:
         app.config.update(test_config)
+    app.config["URL_PREFIX"] = normalize_url_prefix(app.config["URL_PREFIX"])
+    app.wsgi_app = UrlPrefixMiddleware(app.wsgi_app, app.config["URL_PREFIX"])
 
     Path(app.config["DATABASE"]).parent.mkdir(parents=True, exist_ok=True)
     with sqlite3.connect(app.config["DATABASE"]) as database:
diff --git a/tests/test_app.py b/tests/test_app.py
index f1612d4..e4f5838 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -1,9 +1,9 @@
 import tempfile
 
-from app import create_app
+from fatima import create_app
 
 
-def client():
+def client(url_prefix="/fatima"):
     database = tempfile.NamedTemporaryFile(suffix=".sqlite")
     app = create_app({
         "TESTING": True,
@@ -11,6 +11,7 @@ def client():
         "APP_USERNAME": "user",
         "APP_PASSWORD": "pass",
         "DATABASE": database.name,
+        "URL_PREFIX": url_prefix,
     })
     test_client = app.test_client()
     test_client._database_file = database
@@ -18,59 +19,79 @@ def client():
 
 
 def test_calendar_requires_login():
-    response = client().get("/")
+    response = client().get("/fatima/")
     assert response.status_code == 302
-    assert response.headers["Location"].endswith("/login")
+    assert response.headers["Location"].endswith("/fatima/login")
+
+
+def test_prefix_applies_to_generated_links_and_static_assets():
+    test_client = client()
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
+    page = test_client.get("/fatima/")
+
+    assert b'href="/fatima/static/styles.css"' in page.data
+    assert b'src="/fatima/static/calendar.js"' in page.data
+    assert b'data-save-url="/fatima/api/choices"' in page.data
+    assert test_client.get("/").status_code == 404
+
+
+def test_url_prefix_is_configurable_and_can_be_disabled():
+    custom_client = client("/calendar")
+    assert custom_client.get("/calendar/").headers["Location"].endswith("/calendar/login")
+    assert custom_client.get("/fatima/").status_code == 404
+
+    root_client = client("")
+    assert root_client.get("/").headers["Location"].endswith("/login")
 
 
 def test_login_and_logout():
     test_client = client()
-    response = test_client.post("/login", data={"username": "user", "password": "pass"})
+    response = test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
     assert response.status_code == 302
-    assert response.headers["Location"].endswith("/")
-    assert test_client.get("/").status_code == 200
-    assert test_client.post("/logout").headers["Location"].endswith("/login")
+    assert response.headers["Location"].endswith("/fatima/")
+    assert test_client.get("/fatima/").status_code == 200
+    assert test_client.post("/fatima/logout").headers["Location"].endswith("/fatima/login")
 
 
 def test_bad_login_shows_error():
-    response = client().post("/login", data={"username": "user", "password": "wrong"})
+    response = client().post("/fatima/login", data={"username": "user", "password": "wrong"})
     assert response.status_code == 200
     assert b"not correct" in response.data
 
 
 def test_choice_is_saved_and_rendered():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
-    response = test_client.post("/api/choices", json={"date": "2026-07-15", "amount": "27.50"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
+    response = test_client.post("/fatima/api/choices", json={"date": "2026-07-15", "amount": "27.50"})
     assert response.status_code == 200
     assert response.json["amount_cents"] == 2750
-    assert b'"2026-07-15": 2750' in test_client.get("/").data
+    assert b'"2026-07-15": 2750' in test_client.get("/fatima/").data
 
 
 def test_choice_rejects_invalid_amount():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
-    response = test_client.post("/api/choices", json={"date": "2026-07-15", "amount": "-1"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
+    response = test_client.post("/fatima/api/choices", json={"date": "2026-07-15", "amount": "-1"})
     assert response.status_code == 400
 
 
 def test_day_status_is_saved_and_rendered():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
     response = test_client.post(
-        "/api/statuses",
+        "/fatima/api/statuses",
         json={"date": "2026-07-15", "status": "vacation"},
     )
     assert response.status_code == 200
     assert response.json["status"] == "vacation"
-    assert b'"2026-07-15": "vacation"' in test_client.get("/").data
+    assert b'"2026-07-15": "vacation"' in test_client.get("/fatima/").data
 
 
 def test_day_status_rejects_unknown_value():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
     response = test_client.post(
-        "/api/statuses",
+        "/fatima/api/statuses",
         json={"date": "2026-07-15", "status": "elsewhere"},
     )
     assert response.status_code == 400
@@ -78,14 +99,14 @@ def test_day_status_rejects_unknown_value():
 
 def test_delete_removes_amount_and_status():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
-    test_client.post("/api/choices", json={"date": "2026-07-15", "amount": "55"})
-    test_client.post("/api/statuses", json={"date": "2026-07-15", "status": "sick"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
+    test_client.post("/fatima/api/choices", json={"date": "2026-07-15", "amount": "55"})
+    test_client.post("/fatima/api/statuses", json={"date": "2026-07-15", "status": "sick"})
 
-    response = test_client.post("/api/delete-date", json={"date": "2026-07-15"})
+    response = test_client.post("/fatima/api/delete-date", json={"date": "2026-07-15"})
     assert response.status_code == 200
     assert response.json["deleted"] is True
-    page = test_client.get("/").data
+    page = test_client.get("/fatima/").data
     assert b'"2026-07-15": 5500' not in page
     assert b'"2026-07-15": "sick"' not in page
 
@@ -94,15 +115,15 @@ def test_report_groups_money_and_days_by_status():
     from datetime import date
 
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
     year = date.today().year
     worked_date = f"{year}-01-10"
     vacation_date = f"{year}-02-10"
-    test_client.post("/api/choices", json={"date": worked_date, "amount": "55"})
-    test_client.post("/api/choices", json={"date": vacation_date, "amount": "27.50"})
-    test_client.post("/api/statuses", json={"date": vacation_date, "status": "vacation"})
+    test_client.post("/fatima/api/choices", json={"date": worked_date, "amount": "55"})
+    test_client.post("/fatima/api/choices", json={"date": vacation_date, "amount": "27.50"})
+    test_client.post("/fatima/api/statuses", json={"date": vacation_date, "status": "vacation"})
 
-    response = test_client.get("/report")
+    response = test_client.get("/fatima/report")
     assert response.status_code == 200
     assert b"\xe2\x82\xac55.00" in response.data
     assert b"\xe2\x82\xac27.50" in response.data
@@ -111,8 +132,8 @@ def test_report_groups_money_and_days_by_status():
 
 def test_report_can_navigate_to_another_year():
     test_client = client()
-    test_client.post("/login", data={"username": "user", "password": "pass"})
-    response = test_client.get("/report?year=2025")
+    test_client.post("/fatima/login", data={"username": "user", "password": "pass"})
+    response = test_client.get("/fatima/report?year=2025")
     assert response.status_code == 200
     assert b"2025 report" in response.data
     assert b"year=2024" in response.data