diff --git a/example/t01-services/synoptic/techui.yaml b/example/t01-services/synoptic/techui.yaml
index ad5a822..616bc73 100644
--- a/example/t01-services/synoptic/techui.yaml
+++ b/example/t01-services/synoptic/techui.yaml
@@ -3,6 +3,7 @@ beamline:
   short_dom: t01
   long_dom: bl01t
   desc: Test Beamline
+  url: t01-opis.diamond.ac.uk
 
 components:
   fshtr:
diff --git a/src/techui_builder/models.py b/src/techui_builder/models.py
index 81091ef..dc1a4f5 100644
--- a/src/techui_builder/models.py
+++ b/src/techui_builder/models.py
@@ -46,6 +46,7 @@
 )
 _LONG_DOM_RE = re.compile(r"^[a-zA-Z]{2}\d{2}[a-zA-Z]$")
 _SHORT_DOM_RE = re.compile(r"^[a-zA-Z]{1}\d{2}(-[0-9]{1})?$")
+_OPIS_URL_RE = re.compile(r"^(https:\/\/)?([a-z0-9]{3}-(?:[0-9]-)?opis(?:.[a-z0-9]*)*)")
 
 
 class Beamline(BaseModel):
@@ -53,6 +54,7 @@ class Beamline(BaseModel):
     long_dom: str = Field(description="Full BL domain e.g. bl23b")
     desc: str = Field(description="Description")
     model_config = ConfigDict(extra="forbid")
+    url: str = Field(description="URL of ixx-opis")
 
     @field_validator("short_dom")
     @classmethod
@@ -75,6 +77,22 @@ def normalize_long_dom(cls, v: str) -> str:
 
         raise ValueError("Invalid long dom.")
 
+    @field_validator("url")
+    @classmethod
+    def check_url(cls, url: str) -> str:
+        url = url.strip().lower()
+        match = _OPIS_URL_RE.match(url)
+        if match is not None and match.group(2):
+            # url in correct format
+            # e.g. t01-opis.diamond.ac.uk
+            if not match.group(1):
+                # make sure url leads with 'https://'
+                # otherwise phoebus treats it as a local file path
+                url = f"https://{match.group(2)}"
+            return url
+
+        raise ValueError("Invalid opis URL.")
+
 
 class Component(BaseModel):
     prefix: str
diff --git a/tests/test_models.py b/tests/test_models.py
index 67e4652..e2691b0 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -10,7 +10,12 @@
 
 @pytest.fixture
 def beamline() -> Beamline:
-    return Beamline(short_dom="t01", long_dom="bl01t", desc="Test Beamline")
+    return Beamline(
+        short_dom="t01",
+        long_dom="bl01t",
+        desc="Test Beamline",
+        url="t01-opis.diamond.ac.uk",
+    )
 
 
 @pytest.fixture
@@ -30,6 +35,7 @@ def test_beamline_object(beamline: Beamline):
     assert beamline.short_dom == "t01"
     assert beamline.long_dom == "bl01t"
     assert beamline.desc == "Test Beamline"
+    assert beamline.url == "https://t01-opis.diamond.ac.uk"
 
 
 def test_component_object(component: Component):