diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4bc8a956f1c..5ec14e9ab6a 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -88,4 +88,4 @@ repos:
         pass_filenames: false
         language: script
         types: [json]
-        files: ^homeassistant/.+/manifest\.json$
+        files: ^homeassistant/.+/(manifest|strings)\.json$
diff --git a/homeassistant/components/deconz/strings.json b/homeassistant/components/deconz/strings.json
index 2293be4b247..ab2d21195fb 100644
--- a/homeassistant/components/deconz/strings.json
+++ b/homeassistant/components/deconz/strings.json
@@ -84,7 +84,7 @@
       "close": "Close",
       "both_buttons": "Both buttons",
       "top_buttons": "Top buttons",
-      "bottom_buttons" : "Bottom buttons",
+      "bottom_buttons": "Bottom buttons",
       "button_1": "First button",
       "button_2": "Second button",
       "button_3": "Third button",
diff --git a/homeassistant/components/unifi/strings.json b/homeassistant/components/unifi/strings.json
index cb7767eba12..50f29de9104 100644
--- a/homeassistant/components/unifi/strings.json
+++ b/homeassistant/components/unifi/strings.json
@@ -57,8 +57,5 @@
         "title": "UniFi options 3/3"
       }
     }
-  },
-  "error": {
-    "unknown_client_mac": "No client available in UniFi on that MAC address"
   }
 }
diff --git a/script/hassfest/__main__.py b/script/hassfest/__main__.py
index a1541ef68c9..7c86a1ca6c4 100644
--- a/script/hassfest/__main__.py
+++ b/script/hassfest/__main__.py
@@ -8,16 +8,15 @@ from . import (
     config_flow,
     coverage,
     dependencies,
-    json,
     manifest,
     services,
     ssdp,
+    translations,
     zeroconf,
 )
 from .model import Config, Integration
 
 PLUGINS = [
-    json,
     codeowners,
     config_flow,
     coverage,
@@ -25,6 +24,7 @@ PLUGINS = [
     manifest,
     services,
     ssdp,
+    translations,
     zeroconf,
 ]
 
diff --git a/script/hassfest/json.py b/script/hassfest/json.py
deleted file mode 100644
index 73b6c372b4f..00000000000
--- a/script/hassfest/json.py
+++ /dev/null
@@ -1,29 +0,0 @@
-"""Validate integration JSON files."""
-import json
-from typing import Dict
-
-from .model import Integration
-
-
-def validate_json_files(integration: Integration):
-    """Validate JSON files for integration."""
-    for json_file in integration.path.glob("**/*.json"):
-        if not json_file.is_file():
-            continue
-
-        try:
-            json.loads(json_file.read_text())
-        except json.JSONDecodeError:
-            relative_path = json_file.relative_to(integration.path)
-            integration.add_error("json", f"Invalid JSON file {relative_path}")
-
-    return
-
-
-def validate(integrations: Dict[str, Integration], config):
-    """Handle JSON files inside integrations."""
-    for integration in integrations.values():
-        if not integration.manifest:
-            continue
-
-        validate_json_files(integration)
diff --git a/script/hassfest/translations.py b/script/hassfest/translations.py
new file mode 100644
index 00000000000..f55e793ad92
--- /dev/null
+++ b/script/hassfest/translations.py
@@ -0,0 +1,90 @@
+"""Validate integration translation files."""
+import json
+from typing import Dict
+
+import voluptuous as vol
+from voluptuous.humanize import humanize_error
+
+from .model import Integration
+
+
+def data_entry_schema(*, require_title: bool, require_step_title: bool):
+    """Generate a data entry schema."""
+    step_title_class = vol.Required if require_step_title else vol.Optional
+    data_entry_schema = {
+        vol.Optional("flow_title"): str,
+        vol.Required("step"): {
+            str: {
+                step_title_class("title"): str,
+                vol.Optional("description"): str,
+                vol.Optional("data"): {str: str},
+            }
+        },
+        vol.Optional("error"): {str: str},
+        vol.Optional("abort"): {str: str},
+        vol.Optional("create_entry"): {str: str},
+    }
+    if require_title:
+        data_entry_schema[vol.Required("title")] = str
+
+    return data_entry_schema
+
+
+STRINGS_SCHEMA = vol.Schema(
+    {
+        vol.Optional("title"): str,
+        vol.Optional("config"): data_entry_schema(
+            require_title=False, require_step_title=True
+        ),
+        vol.Optional("options"): data_entry_schema(
+            require_title=False, require_step_title=False
+        ),
+        vol.Optional("device_automation"): {
+            vol.Optional("action_type"): {str: str},
+            vol.Optional("condition_type"): {str: str},
+            vol.Optional("trigger_type"): {str: str},
+            vol.Optional("trigger_subtype"): {str: str},
+        },
+        vol.Optional("state"): {str: str},
+    }
+)
+
+AUTH_SCHEMA = vol.Schema(
+    {
+        vol.Optional("mfa_setup"): {
+            str: data_entry_schema(require_title=True, require_step_title=True)
+        }
+    }
+)
+
+ONBOARDING_SCHEMA = vol.Schema({vol.Required("area"): {str: str}})
+
+
+def validate_translation_file(integration: Integration):
+    """Validate translation files for integration."""
+    strings_file = integration.path / "strings.json"
+
+    if not strings_file.is_file():
+        return
+
+    strings = json.loads(strings_file.read_text())
+
+    if integration.domain == "auth":
+        schema = AUTH_SCHEMA
+    elif integration.domain == "onboarding":
+        schema = ONBOARDING_SCHEMA
+    else:
+        schema = STRINGS_SCHEMA
+
+    try:
+        schema(strings)
+    except vol.Invalid as err:
+        integration.add_error(
+            "translations", f"Invalid strings.json: {humanize_error(strings, err)}"
+        )
+
+
+def validate(integrations: Dict[str, Integration], config):
+    """Handle JSON files inside integrations."""
+    for integration in integrations.values():
+        validate_translation_file(integration)
diff --git a/script/translations/__main__.py b/script/translations/__main__.py
index 3b64b4168c2..52a39038107 100644
--- a/script/translations/__main__.py
+++ b/script/translations/__main__.py
@@ -21,9 +21,7 @@ def main():
     args = get_arguments()
 
     module = importlib.import_module(f".{args.action}", "script.translations")
-    module.run()
-
-    return 0
+    return module.run()
 
 
 if __name__ == "__main__":
diff --git a/script/translations/clean.py b/script/translations/clean.py
index 348b8ca6c4d..57e23bee9df 100644
--- a/script/translations/clean.py
+++ b/script/translations/clean.py
@@ -68,3 +68,5 @@ def run():
 
     print("Deleting keys:", ", ".join(map(str, to_delete)))
     print(lokalise.keys_delete_multiple(to_delete))
+
+    return 0
diff --git a/script/translations/develop.py b/script/translations/develop.py
index 27f3a884335..8886debd555 100644
--- a/script/translations/develop.py
+++ b/script/translations/develop.py
@@ -61,3 +61,5 @@ def run():
     )
 
     download.write_integration_translations()
+
+    return 0
diff --git a/script/translations/download.py b/script/translations/download.py
index 2191a8195a8..e6e4415f16d 100755
--- a/script/translations/download.py
+++ b/script/translations/download.py
@@ -149,3 +149,5 @@ def run():
     run_download_docker()
 
     write_integration_translations()
+
+    return 0
diff --git a/script/translations/migrate.py b/script/translations/migrate.py
index 644bfec5b30..7026aef2840 100644
--- a/script/translations/migrate.py
+++ b/script/translations/migrate.py
@@ -48,3 +48,5 @@ def run():
     print()
     print("Updating keys")
     pprint(lokalise.keys_bulk_update(updates).json())
+
+    return 0
diff --git a/script/translations/upload.py b/script/translations/upload.py
index cf14ffa3cf9..ecd9ec405df 100755
--- a/script/translations/upload.py
+++ b/script/translations/upload.py
@@ -82,3 +82,5 @@ def run():
     LOCAL_FILE.write_text(json.dumps(translations, indent=4, sort_keys=True))
 
     run_upload_docker()
+
+    return 0
diff --git a/script/translations/util.py b/script/translations/util.py
index 02a7d577e66..ad415481e8e 100644
--- a/script/translations/util.py
+++ b/script/translations/util.py
@@ -13,7 +13,7 @@ def get_base_arg_parser():
     parser.add_argument(
         "action",
         type=str,
-        choices=["download", "clean", "upload", "develop", "migrate"],
+        choices=["clean", "develop", "download", "migrate", "upload"],
     )
     parser.add_argument("--debug", action="store_true", help="Enable log output")
     return parser