diff --git a/halfapi/lib/constants.py b/halfapi/lib/constants.py
index 562c174..294fec9 100644
--- a/halfapi/lib/constants.py
+++ b/halfapi/lib/constants.py
@@ -1 +1,27 @@
+from schema import Schema, Optional
+
 VERBS = ('GET', 'POST', 'PUT', 'PATCH', 'DELETE')
+
+ACLS_SCHEMA = Schema([{
+    'acl': str,
+    Optional('args'): {
+        Optional('required'): { str },
+        Optional('optional'): { str }
+    },
+    Optional('out'): { str }
+}])
+
+ROUTE_SCHEMA = Schema({
+    str: {
+        'docs': lambda n: True, # Should validate an openAPI spec
+        'acls': ACLS_SCHEMA
+    }
+})
+
+DOMAIN_SCHEMA = Schema({
+    str: ROUTE_SCHEMA
+})
+
+API_SCHEMA = Schema({
+    str: DOMAIN_SCHEMA # key: domain name, value: result of lib.routes.api_routes(domain_module)
+})
diff --git a/tests/test_constants.py b/tests/test_constants.py
new file mode 100644
index 0000000..c9cd49c
--- /dev/null
+++ b/tests/test_constants.py
@@ -0,0 +1,14 @@
+from schema import Schema
+def test_constants():
+    from halfapi.lib.constants import (
+        VERBS,
+        ACLS_SCHEMA,
+        ROUTE_SCHEMA,
+        DOMAIN_SCHEMA,
+        API_SCHEMA)
+
+    assert isinstance(VERBS, tuple)
+    assert isinstance(ACLS_SCHEMA, Schema)
+    assert isinstance(ROUTE_SCHEMA, Schema)
+    assert isinstance(DOMAIN_SCHEMA, Schema)
+    assert isinstance(API_SCHEMA, Schema)