diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b4dbcb1..54f7158 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,10 +1,6 @@
 name: Tests
 
-on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
+on: push
 
 jobs:
   api-unit-tests:
diff --git a/LLSP-API/api.py b/LLSP-API/api.py
index a102afa..6b3b476 100644
--- a/LLSP-API/api.py
+++ b/LLSP-API/api.py
@@ -7,10 +7,12 @@
 
 import logging
 import os
-from typing import Any
+import sys
+from typing import Annotated, Any
 
 from celery import Celery  # type: ignore
-from fastapi import FastAPI
+from fastapi import Depends, FastAPI, HTTPException
+from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 from model import ExecIn, Task, TaskState
 from utils import map_state
 
@@ -19,6 +21,8 @@
 BACKEND = os.getenv("CELERY_RESULT_BACKEND", "rpc://")
 TASK_NAME = os.getenv("EXEC_TASK_NAME", "celery_app.exec_script")
 
+logger = logging.getLogger(__name__)
+
 
 class EndpointFilter(logging.Filter):
     """Filter out log messages containing /healthz or /ready."""
@@ -36,15 +40,29 @@ def filter(self, record: logging.LogRecord) -> bool:
 
 app = FastAPI(title="Exec API")
 
+security = HTTPBearer()
+
+
+def verify_api_key(credentials: Annotated[HTTPAuthorizationCredentials, Depends(security)]) -> None:
+    """
+    Validate the API key from the request credentials.
+
+    :param credentials: The HTTP authorization credentials from the request.
+    :return: True if the API key matches the environment variable, False otherwise.
+    """
+    if credentials.credentials != os.environ.get("LLSP_API_KEY"):
+        raise HTTPException(status_code=401, detail="Invalid API key")
+
 
 @app.post("/execute")
-def execute(payload: ExecIn) -> Task:
+def execute(payload: ExecIn, credentials: Annotated[HTTPAuthorizationCredentials, Depends(security)]) -> Task:
     """
     Submit a script for execution.
 
     :param payload: The script submission payload.
     :return: A `Task` object containing the task ID and initial status.
     """
+    verify_api_key(credentials)
     async_result = celery.send_task(
         TASK_NAME,
         args=[payload.script],
@@ -53,13 +71,14 @@ def execute(payload: ExecIn) -> Task:
 
 
 @app.get("/status/{task_id}")
-def status(task_id: str) -> Task:
+def status(task_id: str, credentials: Annotated[HTTPAuthorizationCredentials, Depends(security)]) -> Task:
     """
     Check the status of a submitted task.
 
     :param task_id: The ID of the task to check.
     :return: A `Task` object with the current state and result (if ready).
     """
+    verify_api_key(credentials)
     res = celery.AsyncResult(task_id)
     body: Any = None
     try:
@@ -96,4 +115,8 @@ def ready() -> dict[str, str]:
 
     :return: A dict indicating the service is ready.
     """
+    api_key = os.environ.get("LLSP_API_KEY", None)
+    if api_key is None:
+        logger.critical("The LLSP_API_KEY environment variable is not set.")
+        sys.exit(1)
     return {"status": "ready"}
diff --git a/LLSP-Worker/Dockerfile b/LLSP-Worker/Dockerfile
index 79a6dd4..51c03f1 100644
--- a/LLSP-Worker/Dockerfile
+++ b/LLSP-Worker/Dockerfile
@@ -1,3 +1,4 @@
+
 FROM ghcr.io/fiaisis/mantid:6.15.0
 ENV PYTHONDONTWRITEBYTECODE=1 PYTHONUNBUFFERED=1
 WORKDIR /app
diff --git a/docker-compose.test.yml b/docker-compose.test.yml
index 6907bdf..058d080 100644
--- a/docker-compose.test.yml
+++ b/docker-compose.test.yml
@@ -19,6 +19,7 @@ services:
       CELERY_BROKER_URL: amqp://llsp:llsp@rabbitmq:5672/llspvhost
       CELERY_RESULT_BACKEND: rpc://
       EXEC_TASK_NAME: celery_app.exec_script
+      LLSP_API_KEY: "secret-token"
     depends_on:
       rabbitmq:
         condition: service_healthy
@@ -50,6 +51,7 @@ services:
       dockerfile: tests/Dockerfile
     environment:
       API_BASE_URL: http://api:8000
+      LLSP_API_KEY: "secret-token"
     depends_on:
       api:
         condition: service_healthy
diff --git a/docker-compose.yml b/docker-compose.yml
index 2a984d3..d7b5808 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -19,6 +19,7 @@ services:
       CELERY_BROKER_URL: amqp://llsp:llsp@rabbitmq:5672/llspvhost
       CELERY_RESULT_BACKEND: rpc://
       EXEC_TASK_NAME: celery_app.exec_script
+      LLSP_API_KEY: "secret-token"
     depends_on:
       rabbitmq:
         condition: service_healthy
diff --git a/tests/e2e/test_submission.py b/tests/e2e/test_submission.py
index cf6f407..5065bf6 100644
--- a/tests/e2e/test_submission.py
+++ b/tests/e2e/test_submission.py
@@ -6,14 +6,15 @@
 
 import os
 import time
+from http import HTTPStatus
 
 import requests
-from tenacity import retry, stop_after_attempt, wait_fixed
 
 API_URL = os.getenv("API_BASE_URL", "http://localhost:8000")
+API_KEY = os.getenv("LLSP_API_KEY", "secret-token")
+HEADERS = {"Authorization": f"Bearer {API_KEY}"}
 
 
-@retry(stop=stop_after_attempt(5), wait=wait_fixed(2))
 def wait_for_api():
     """
     Wait for the API to become responsive.
@@ -45,7 +46,12 @@ def test_workflow():
 print('Hello from stdout')
 print('Hello from stderr', file=sys.stderr)
 """
-    response = requests.post(f"{API_URL}/execute", json={"script": script}, timeout=10)
+    response = requests.post(
+        f"{API_URL}/execute",
+        json={"script": script},
+        headers=HEADERS,
+        timeout=10,
+    )
     response.raise_for_status()
     data = response.json()
     assert "task_id" in data
@@ -53,7 +59,11 @@ def test_workflow():
 
     # 2. Poll for Status
     for _ in range(30):
-        response = requests.get(f"{API_URL}/status/{task_id}", timeout=10)
+        response = requests.get(
+            f"{API_URL}/status/{task_id}",
+            headers=HEADERS,
+            timeout=10,
+        )
         response.raise_for_status()
         state = response.json()
         if state["state"] in ["success", "error"]:
@@ -70,5 +80,23 @@ def test_workflow():
     assert "Hello from stderr" in result["stderr"]
 
 
-if __name__ == "__main__":
-    test_workflow()
+def test_unauthorized_access():
+    """Verify that requests without a valid API key are rejected."""
+    wait_for_api()
+
+    # Case 1: No Authorization header
+    response = requests.post(
+        f"{API_URL}/execute",
+        json={"script": "print('fail')"},
+        timeout=10,
+    )
+    assert response.status_code == HTTPStatus.FORBIDDEN, f"Expected 403, got {response.status_code}"
+
+    # Case 2: Invalid API key
+    response = requests.post(
+        f"{API_URL}/execute",
+        json={"script": "print('fail')"},
+        headers={"Authorization": "Bearer invalid-token"},
+        timeout=10,
+    )
+    assert response.status_code == HTTPStatus.UNAUTHORIZED, f"Expected 401, got {response.status_code}"