diff --git a/script/hassfest/__main__.py b/script/hassfest/__main__.py
index 27252969118..87024619765 100644
--- a/script/hassfest/__main__.py
+++ b/script/hassfest/__main__.py
@@ -1,4 +1,6 @@
 """Validate manifests."""
+from __future__ import annotations
+
 import argparse
 import pathlib
 import sys
@@ -55,7 +57,7 @@ ALL_PLUGIN_NAMES = [
 ]
 
 
-def valid_integration_path(integration_path):
+def valid_integration_path(integration_path: pathlib.Path | str) -> pathlib.Path:
     """Test if it's a valid integration."""
     path = pathlib.Path(integration_path)
     if not path.is_dir():
@@ -124,7 +126,7 @@ def get_config() -> Config:
     )
 
 
-def main():
+def main() -> int:
     """Validate manifests."""
     try:
         config = get_config()
@@ -218,7 +220,12 @@ def main():
     return 1
 
 
-def print_integrations_status(config, integrations, *, show_fixable_errors=True):
+def print_integrations_status(
+    config: Config,
+    integrations: list[Integration],
+    *,
+    show_fixable_errors: bool = True,
+) -> None:
     """Print integration status."""
     for integration in sorted(integrations, key=lambda itg: itg.domain):
         extra = f" - {integration.path}" if config.specific_integrations else ""
diff --git a/script/hassfest/application_credentials.py b/script/hassfest/application_credentials.py
index aed8b892f50..1be644054c4 100644
--- a/script/hassfest/application_credentials.py
+++ b/script/hassfest/application_credentials.py
@@ -41,7 +41,7 @@ def validate(integrations: dict[str, Integration], config: Config) -> None:
         )
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate application_credentials data."""
     application_credentials_path = (
         config.root / "homeassistant/generated/application_credentials.py"
diff --git a/script/hassfest/bluetooth.py b/script/hassfest/bluetooth.py
index 57772edd7f4..a4b2ffc8cb1 100644
--- a/script/hassfest/bluetooth.py
+++ b/script/hassfest/bluetooth.py
@@ -5,7 +5,7 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: list[dict[str, str]]):
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate bluetooth data."""
     match_list = []
 
@@ -29,7 +29,7 @@ def generate_and_validate(integrations: list[dict[str, str]]):
     )
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate bluetooth file."""
     bluetooth_path = config.root / "homeassistant/generated/bluetooth.py"
     config.cache["bluetooth"] = content = generate_and_validate(integrations)
@@ -48,7 +48,7 @@ def validate(integrations: dict[str, Integration], config: Config):
         return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate bluetooth file."""
     bluetooth_path = config.root / "homeassistant/generated/bluetooth.py"
     with open(str(bluetooth_path), "w") as fp:
diff --git a/script/hassfest/brand.py b/script/hassfest/brand.py
index c35f50599ff..1083cc911bd 100644
--- a/script/hassfest/brand.py
+++ b/script/hassfest/brand.py
@@ -55,7 +55,7 @@ def _validate_brand(
     ):
         config.add_error(
             "brand",
-            f"{brand.path.name}: Brand '{brand.brand['domain']}' "
+            f"{brand.path.name}: Brand '{brand.domain}' "
             f"is an integration but is missing in the brand's 'integrations' list'",
         )
 
diff --git a/script/hassfest/codeowners.py b/script/hassfest/codeowners.py
index 0cc58012162..c300976c193 100644
--- a/script/hassfest/codeowners.py
+++ b/script/hassfest/codeowners.py
@@ -42,7 +42,7 @@ REMOVE_CODEOWNERS = """
 """
 
 
-def generate_and_validate(integrations: dict[str, Integration], config: Config):
+def generate_and_validate(integrations: dict[str, Integration], config: Config) -> str:
     """Generate CODEOWNERS."""
     parts = [BASE]
 
@@ -77,7 +77,7 @@ def generate_and_validate(integrations: dict[str, Integration], config: Config):
     return "\n".join(parts)
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate CODEOWNERS."""
     codeowners_path = config.root / "CODEOWNERS"
     config.cache["codeowners"] = content = generate_and_validate(integrations, config)
@@ -95,7 +95,7 @@ def validate(integrations: dict[str, Integration], config: Config):
         return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate CODEOWNERS."""
     codeowners_path = config.root / "CODEOWNERS"
     with open(str(codeowners_path), "w") as fp:
diff --git a/script/hassfest/config_flow.py b/script/hassfest/config_flow.py
index e668846505f..2c3988cc488 100644
--- a/script/hassfest/config_flow.py
+++ b/script/hassfest/config_flow.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 
 import json
 import pathlib
+from typing import Any
 
 from .brand import validate as validate_brands
 from .model import Brand, Config, Integration
@@ -11,12 +12,12 @@ from .serializer import format_python_namespace
 UNIQUE_ID_IGNORE = {"huawei_lte", "mqtt", "adguard"}
 
 
-def _validate_integration(config: Config, integration: Integration):
+def _validate_integration(config: Config, integration: Integration) -> None:
     """Validate config flow of an integration."""
     config_flow_file = integration.path / "config_flow.py"
 
     if not config_flow_file.is_file():
-        if integration.manifest.get("config_flow"):
+        if (integration.manifest or {}).get("config_flow"):
             integration.add_error(
                 "config_flow",
                 "Config flows need to be defined in the file config_flow.py",
@@ -60,9 +61,9 @@ def _validate_integration(config: Config, integration: Integration):
     )
 
 
-def _generate_and_validate(integrations: dict[str, Integration], config: Config):
+def _generate_and_validate(integrations: dict[str, Integration], config: Config) -> str:
     """Validate and generate config flow data."""
-    domains = {
+    domains: dict[str, list[str]] = {
         "integration": [],
         "helper": [],
     }
@@ -84,9 +85,9 @@ def _generate_and_validate(integrations: dict[str, Integration], config: Config)
 
 
 def _populate_brand_integrations(
-    integration_data: dict,
+    integration_data: dict[str, Any],
     integrations: dict[str, Integration],
-    brand_metadata: dict,
+    brand_metadata: dict[str, Any],
     sub_integrations: list[str],
 ) -> None:
     """Add referenced integrations to a brand's metadata."""
@@ -99,7 +100,7 @@ def _populate_brand_integrations(
             "system",
         ):
             continue
-        metadata = {
+        metadata: dict[str, Any] = {
             "integration_type": integration.integration_type,
         }
         # Always set the config_flow key to avoid breaking the frontend
@@ -119,11 +120,13 @@ def _populate_brand_integrations(
 
 
 def _generate_integrations(
-    brands: dict[str, Brand], integrations: dict[str, Integration], config: Config
-):
+    brands: dict[str, Brand],
+    integrations: dict[str, Integration],
+    config: Config,
+) -> str:
     """Generate integrations data."""
 
-    result = {
+    result: dict[str, Any] = {
         "integration": {},
         "helper": {},
         "translated_name": set(),
@@ -154,7 +157,7 @@ def _generate_integrations(
 
     # Generate the config flow index
     for domain in sorted(primary_domains):
-        metadata = {}
+        metadata: dict[str, Any] = {}
 
         if brand := brands.get(domain):
             metadata["name"] = brand.name
@@ -199,7 +202,7 @@ def _generate_integrations(
     )
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate config flow file."""
     config_flow_path = config.root / "homeassistant/generated/config_flows.py"
     integrations_path = config.root / "homeassistant/generated/integrations.json"
@@ -233,7 +236,7 @@ def validate(integrations: dict[str, Integration], config: Config):
             )
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate config flow file."""
     config_flow_path = config.root / "homeassistant/generated/config_flows.py"
     integrations_path = config.root / "homeassistant/generated/integrations.json"
diff --git a/script/hassfest/coverage.py b/script/hassfest/coverage.py
index 7c259adbfa3..71d2e3ce57c 100644
--- a/script/hassfest/coverage.py
+++ b/script/hassfest/coverage.py
@@ -30,7 +30,7 @@ ALLOWED_IGNORE_VIOLATIONS = {
 }
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate coverage."""
     coverage_path = config.root / ".coveragerc"
 
diff --git a/script/hassfest/dependencies.py b/script/hassfest/dependencies.py
index b5d82f7b348..fae628270af 100644
--- a/script/hassfest/dependencies.py
+++ b/script/hassfest/dependencies.py
@@ -7,19 +7,19 @@ from pathlib import Path
 from homeassistant.const import Platform
 from homeassistant.requirements import DISCOVERY_INTEGRATIONS
 
-from .model import Integration
+from .model import Config, Integration
 
 
 class ImportCollector(ast.NodeVisitor):
     """Collect all integrations referenced."""
 
-    def __init__(self, integration: Integration):
+    def __init__(self, integration: Integration) -> None:
         """Initialize the import collector."""
         self.integration = integration
         self.referenced: dict[Path, set[str]] = {}
 
         # Current file or dir we're inspecting
-        self._cur_fil_dir = None
+        self._cur_fil_dir: Path | None = None
 
     def collect(self) -> None:
         """Collect imports from a source file."""
@@ -32,11 +32,12 @@ class ImportCollector(ast.NodeVisitor):
             self.visit(ast.parse(fil.read_text()))
             self._cur_fil_dir = None
 
-    def _add_reference(self, reference_domain: str):
+    def _add_reference(self, reference_domain: str) -> None:
         """Add a reference."""
+        assert self._cur_fil_dir
         self.referenced[self._cur_fil_dir].add(reference_domain)
 
-    def visit_ImportFrom(self, node):
+    def visit_ImportFrom(self, node: ast.ImportFrom) -> None:
         """Visit ImportFrom node."""
         if node.module is None:
             return
@@ -59,14 +60,14 @@ class ImportCollector(ast.NodeVisitor):
             for name_node in node.names:
                 self._add_reference(name_node.name)
 
-    def visit_Import(self, node):
+    def visit_Import(self, node: ast.Import) -> None:
         """Visit Import node."""
         # import homeassistant.components.hue as hue
         for name_node in node.names:
             if name_node.name.startswith("homeassistant.components."):
                 self._add_reference(name_node.name.split(".")[2])
 
-    def visit_Attribute(self, node):
+    def visit_Attribute(self, node: ast.Attribute) -> None:
         """Visit Attribute node."""
         # hass.components.hue.async_create()
         # Name(id=hass)
@@ -156,15 +157,16 @@ IGNORE_VIOLATIONS = {
 
 def calc_allowed_references(integration: Integration) -> set[str]:
     """Return a set of allowed references."""
+    manifest = integration.manifest
     allowed_references = (
         ALLOWED_USED_COMPONENTS
-        | set(integration.manifest.get("dependencies", []))
-        | set(integration.manifest.get("after_dependencies", []))
+        | set(manifest.get("dependencies", []))
+        | set(manifest.get("after_dependencies", []))
     )
 
     # Discovery requirements are ok if referenced in manifest
     for check_domain, to_check in DISCOVERY_INTEGRATIONS.items():
-        if any(check in integration.manifest for check in to_check):
+        if any(check in manifest for check in to_check):
             allowed_references.add(check_domain)
 
     return allowed_references
@@ -174,7 +176,7 @@ def find_non_referenced_integrations(
     integrations: dict[str, Integration],
     integration: Integration,
     references: dict[Path, set[str]],
-):
+) -> set[str]:
     """Find intergrations that are not allowed to be referenced."""
     allowed_references = calc_allowed_references(integration)
     referenced = set()
@@ -219,8 +221,9 @@ def find_non_referenced_integrations(
 
 
 def validate_dependencies(
-    integrations: dict[str, Integration], integration: Integration
-):
+    integrations: dict[str, Integration],
+    integration: Integration,
+) -> None:
     """Validate all dependencies."""
     # Some integrations are allowed to have violations.
     if integration.domain in IGNORE_VIOLATIONS:
@@ -242,7 +245,7 @@ def validate_dependencies(
         )
 
 
-def validate(integrations: dict[str, Integration], config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Handle dependencies for integrations."""
     # check for non-existing dependencies
     for integration in integrations.values():
diff --git a/script/hassfest/dhcp.py b/script/hassfest/dhcp.py
index 992e1f615a1..c143f5940c1 100644
--- a/script/hassfest/dhcp.py
+++ b/script/hassfest/dhcp.py
@@ -5,7 +5,7 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: list[dict[str, str]]):
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate dhcp data."""
     match_list = []
 
@@ -29,7 +29,7 @@ def generate_and_validate(integrations: list[dict[str, str]]):
     )
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate dhcp file."""
     dhcp_path = config.root / "homeassistant/generated/dhcp.py"
     config.cache["dhcp"] = content = generate_and_validate(integrations)
@@ -48,7 +48,7 @@ def validate(integrations: dict[str, Integration], config: Config):
         return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate dhcp file."""
     dhcp_path = config.root / "homeassistant/generated/dhcp.py"
     with open(str(dhcp_path), "w") as fp:
diff --git a/script/hassfest/json.py b/script/hassfest/json.py
index 49ebb05bbea..f0eae9f4152 100644
--- a/script/hassfest/json.py
+++ b/script/hassfest/json.py
@@ -3,10 +3,10 @@ from __future__ import annotations
 
 import json
 
-from .model import Integration
+from .model import Config, Integration
 
 
-def validate_json_files(integration: Integration):
+def validate_json_files(integration: Integration) -> None:
     """Validate JSON files for integration."""
     for json_file in integration.path.glob("**/*.json"):
         if not json_file.is_file():
@@ -18,10 +18,8 @@ def validate_json_files(integration: Integration):
             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):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Handle JSON files inside integrations."""
     if not config.specific_integrations:
         return
diff --git a/script/hassfest/manifest.py b/script/hassfest/manifest.py
index b4130de1dee..ecf04648330 100644
--- a/script/hassfest/manifest.py
+++ b/script/hassfest/manifest.py
@@ -119,7 +119,7 @@ def documentation_url(value: str) -> str:
     return value
 
 
-def verify_lowercase(value: str):
+def verify_lowercase(value: str) -> str:
     """Verify a value is lowercase."""
     if value.lower() != value:
         raise vol.Invalid("Value needs to be lowercase")
@@ -127,7 +127,7 @@ def verify_lowercase(value: str):
     return value
 
 
-def verify_uppercase(value: str):
+def verify_uppercase(value: str) -> str:
     """Verify a value is uppercase."""
     if value.upper() != value:
         raise vol.Invalid("Value needs to be uppercase")
@@ -135,7 +135,7 @@ def verify_uppercase(value: str):
     return value
 
 
-def verify_version(value: str):
+def verify_version(value: str) -> str:
     """Verify the version."""
     try:
         AwesomeVersion(
@@ -153,7 +153,7 @@ def verify_version(value: str):
     return value
 
 
-def verify_wildcard(value: str):
+def verify_wildcard(value: str) -> str:
     """Verify the matcher contains a wildcard."""
     if "*" not in value:
         raise vol.Invalid(f"'{value}' needs to contain a wildcard matcher")
@@ -286,13 +286,13 @@ CUSTOM_INTEGRATION_MANIFEST_SCHEMA = INTEGRATION_MANIFEST_SCHEMA.extend(
 )
 
 
-def validate_version(integration: Integration):
+def validate_version(integration: Integration) -> None:
     """
     Validate the version of the integration.
 
     Will be removed when the version key is no longer optional for custom integrations.
     """
-    if not integration.manifest.get("version"):
+    if not (integration.manifest and integration.manifest.get("version")):
         integration.add_error("manifest", "No 'version' key in the manifest file.")
         return
 
diff --git a/script/hassfest/model.py b/script/hassfest/model.py
index fa1580b0317..ee0a3ab32d9 100644
--- a/script/hassfest/model.py
+++ b/script/hassfest/model.py
@@ -25,7 +25,7 @@ class Error:
 class Config:
     """Config for the run."""
 
-    specific_integrations: pathlib.Path | None = attr.ib()
+    specific_integrations: list[pathlib.Path] | None = attr.ib()
     root: pathlib.Path = attr.ib()
     action: str = attr.ib()
     requirements: bool = attr.ib()
diff --git a/script/hassfest/mqtt.py b/script/hassfest/mqtt.py
index 46ba4dfcf44..d83cb95391a 100644
--- a/script/hassfest/mqtt.py
+++ b/script/hassfest/mqtt.py
@@ -7,7 +7,7 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: dict[str, Integration]):
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate MQTT data."""
 
     data = defaultdict(list)
@@ -29,7 +29,7 @@ def generate_and_validate(integrations: dict[str, Integration]):
     return format_python_namespace({"MQTT": data})
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate MQTT file."""
     mqtt_path = config.root / "homeassistant/generated/mqtt.py"
     config.cache["mqtt"] = content = generate_and_validate(integrations)
@@ -44,10 +44,9 @@ def validate(integrations: dict[str, Integration], config: Config):
                 "File mqtt.py is not up to date. Run python3 -m script.hassfest",
                 fixable=True,
             )
-        return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate MQTT file."""
     mqtt_path = config.root / "homeassistant/generated/mqtt.py"
     with open(str(mqtt_path), "w") as fp:
diff --git a/script/hassfest/requirements.py b/script/hassfest/requirements.py
index 0e72e2eabd6..74fed8b7c7c 100644
--- a/script/hassfest/requirements.py
+++ b/script/hassfest/requirements.py
@@ -8,6 +8,7 @@ import os
 import re
 import subprocess
 import sys
+from typing import Any
 
 from awesomeversion import AwesomeVersion, AwesomeVersionStrategy
 from stdlib_list import stdlib_list
@@ -53,7 +54,7 @@ IGNORE_VIOLATIONS = {
 }
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Handle requirements for integrations."""
     # Check if we are doing format-only validation.
     if not config.requirements:
@@ -63,7 +64,7 @@ def validate(integrations: dict[str, Integration], config: Config):
 
     # check for incompatible requirements
 
-    disable_tqdm = config.specific_integrations or os.environ.get("CI", False)
+    disable_tqdm = bool(config.specific_integrations or os.environ.get("CI"))
 
     for integration in tqdm(integrations.values(), disable=disable_tqdm):
         if not integration.manifest:
@@ -87,7 +88,13 @@ def validate_requirements_format(integration: Integration) -> bool:
             )
             continue
 
-        pkg, sep, version = PACKAGE_REGEX.match(req).groups()
+        if not (match := PACKAGE_REGEX.match(req)):
+            integration.add_error(
+                "requirements",
+                f'Requirement "{req}" does not match package regex pattern',
+            )
+            continue
+        pkg, sep, version = match.groups()
 
         if integration.core and sep != "==":
             integration.add_error(
@@ -115,7 +122,7 @@ def validate_requirements_format(integration: Integration) -> bool:
     return len(integration.errors) == start_errors
 
 
-def validate_requirements(integration: Integration):
+def validate_requirements(integration: Integration) -> None:
     """Validate requirements."""
     if not validate_requirements_format(integration):
         return
@@ -167,7 +174,7 @@ def validate_requirements(integration: Integration):
 
 
 @cache
-def get_pipdeptree():
+def get_pipdeptree() -> dict[str, dict[str, Any]]:
     """Get pipdeptree output. Cached on first invocation.
 
     {
@@ -254,7 +261,7 @@ def install_requirements(integration: Integration, requirements: set[str]) -> bo
         if normalized and "==" in requirement_arg:
             ver = requirement_arg.split("==")[-1]
             item = deptree.get(normalized)
-            is_installed = item and item["installed_version"] == ver
+            is_installed = bool(item and item["installed_version"] == ver)
 
         if not is_installed:
             try:
diff --git a/script/hassfest/serializer.py b/script/hassfest/serializer.py
index 5ba386148f3..101aea6837e 100644
--- a/script/hassfest/serializer.py
+++ b/script/hassfest/serializer.py
@@ -5,6 +5,7 @@ from collections.abc import Collection, Iterable, Mapping
 from typing import Any
 
 import black
+from black.mode import Mode
 
 DEFAULT_GENERATOR = "script.hassfest"
 
@@ -13,7 +14,7 @@ def _wrap_items(
     items: Iterable[str],
     opener: str,
     closer: str,
-    sort=False,
+    sort: bool = False,
 ) -> str:
     """Wrap pre-formatted Python reprs in braces, optionally sorting them."""
     # The trailing comma is imperative so Black doesn't format some items
@@ -23,7 +24,7 @@ def _wrap_items(
     return f"{opener}{','.join(items)},{closer}"
 
 
-def _mapping_to_str(data: Mapping) -> str:
+def _mapping_to_str(data: Mapping[Any, Any]) -> str:
     """Return a string representation of a mapping."""
     return _wrap_items(
         (f"{to_string(key)}:{to_string(value)}" for key, value in data.items()),
@@ -34,7 +35,10 @@ def _mapping_to_str(data: Mapping) -> str:
 
 
 def _collection_to_str(
-    data: Collection, opener: str = "[", closer: str = "]", sort=False
+    data: Collection[Any],
+    opener: str = "[",
+    closer: str = "]",
+    sort: bool = False,
 ) -> str:
     """Return a string representation of a collection."""
     items = (to_string(value) for value in data)
@@ -66,7 +70,7 @@ To update, run python3 -m {generator}
 
 {content}
 """
-    return black.format_str(content.strip(), mode=black.Mode())
+    return black.format_str(content.strip(), mode=Mode())
 
 
 def format_python_namespace(
diff --git a/script/hassfest/services.py b/script/hassfest/services.py
index a5d10f8dda5..f7070d2dc5f 100644
--- a/script/hassfest/services.py
+++ b/script/hassfest/services.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 
 import pathlib
 import re
+from typing import Any
 
 import voluptuous as vol
 from voluptuous.humanize import humanize_error
@@ -12,10 +13,10 @@ from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import config_validation as cv, selector
 from homeassistant.util.yaml import load_yaml
 
-from .model import Integration
+from .model import Config, Integration
 
 
-def exists(value):
+def exists(value: Any) -> Any:
     """Check if value exists."""
     if value is None:
         raise vol.Invalid("Value cannot be None")
@@ -63,7 +64,7 @@ def grep_dir(path: pathlib.Path, glob_pattern: str, search_pattern: str) -> bool
     return False
 
 
-def validate_services(integration: Integration):
+def validate_services(integration: Integration) -> None:
     """Validate services."""
     try:
         data = load_yaml(str(integration.path / "services.yaml"))
@@ -92,7 +93,7 @@ def validate_services(integration: Integration):
         )
 
 
-def validate(integrations: dict[str, Integration], config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Handle dependencies for integrations."""
     # check services.yaml is cool
     for integration in integrations.values():
diff --git a/script/hassfest/ssdp.py b/script/hassfest/ssdp.py
index cbe0c3ee76f..aebead6e97f 100644
--- a/script/hassfest/ssdp.py
+++ b/script/hassfest/ssdp.py
@@ -7,7 +7,7 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: dict[str, Integration]):
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate ssdp data."""
 
     data = defaultdict(list)
@@ -29,7 +29,7 @@ def generate_and_validate(integrations: dict[str, Integration]):
     return format_python_namespace({"SSDP": data})
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate ssdp file."""
     ssdp_path = config.root / "homeassistant/generated/ssdp.py"
     config.cache["ssdp"] = content = generate_and_validate(integrations)
@@ -44,10 +44,9 @@ def validate(integrations: dict[str, Integration], config: Config):
                 "File ssdp.py is not up to date. Run python3 -m script.hassfest",
                 fixable=True,
             )
-        return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate ssdp file."""
     ssdp_path = config.root / "homeassistant/generated/ssdp.py"
     with open(str(ssdp_path), "w") as fp:
diff --git a/script/hassfest/translations.py b/script/hassfest/translations.py
index ab2961e0506..8f2816e503c 100644
--- a/script/hassfest/translations.py
+++ b/script/hassfest/translations.py
@@ -5,6 +5,7 @@ from functools import partial
 from itertools import chain
 import json
 import re
+from typing import Any
 
 import voluptuous as vol
 from voluptuous.humanize import humanize_error
@@ -51,7 +52,7 @@ MOVED_TRANSLATIONS_DIRECTORY_MSG = (
 )
 
 
-def allow_name_translation(integration: Integration):
+def allow_name_translation(integration: Integration) -> bool:
     """Validate that the translation name is not the same as the integration name."""
     # Only enforce for core because custom integrations can't be
     # added to allow list.
@@ -74,7 +75,11 @@ def check_translations_directory_name(integration: Integration) -> None:
         integration.add_error("translations", MOVED_TRANSLATIONS_DIRECTORY_MSG)
 
 
-def find_references(strings, prefix, found):
+def find_references(
+    strings: dict[str, Any],
+    prefix: str,
+    found: list[dict[str, str]],
+) -> None:
     """Find references."""
     for key, value in strings.items():
         if isinstance(value, dict):
@@ -87,7 +92,11 @@ def find_references(strings, prefix, found):
             found.append({"source": f"{prefix}::{key}", "ref": match.groups()[0]})
 
 
-def removed_title_validator(config, integration, value):
+def removed_title_validator(
+    config: Config,
+    integration: Integration,
+    value: Any,
+) -> Any:
     """Mark removed title."""
     if not config.specific_integrations:
         raise vol.Invalid(REMOVED_TITLE_MSG)
@@ -97,7 +106,7 @@ def removed_title_validator(config, integration, value):
     return value
 
 
-def lowercase_validator(value):
+def lowercase_validator(value: str) -> str:
     """Validate value is lowercase."""
     if value.lower() != value:
         raise vol.Invalid("Needs to be lowercase")
@@ -112,7 +121,7 @@ def gen_data_entry_schema(
     flow_title: int,
     require_step_title: bool,
     mandatory_description: str | None = None,
-):
+) -> vol.All:
     """Generate a data entry schema."""
     step_title_class = vol.Required if require_step_title else vol.Optional
     schema = {
@@ -138,7 +147,7 @@ def gen_data_entry_schema(
             removed_title_validator, config, integration
         )
 
-    def data_description_validator(value):
+    def data_description_validator(value: dict[str, Any]) -> dict[str, Any]:
         """Validate data description."""
         for step_info in value["step"].values():
             if "data_description" not in step_info:
@@ -154,7 +163,7 @@ def gen_data_entry_schema(
 
     if mandatory_description is not None:
 
-        def validate_description_set(value):
+        def validate_description_set(value: dict[str, Any]) -> dict[str, Any]:
             """Validate description is set."""
             steps = value["step"]
             if mandatory_description not in steps:
@@ -169,7 +178,7 @@ def gen_data_entry_schema(
 
     if not allow_name_translation(integration):
 
-        def name_validator(value):
+        def name_validator(value: dict[str, Any]) -> dict[str, Any]:
             """Validate name."""
             for step_id, info in value["step"].items():
                 if info.get("title") == integration.name:
@@ -250,7 +259,7 @@ def gen_strings_schema(config: Config, integration: Integration) -> vol.Schema:
     )
 
 
-def gen_auth_schema(config: Config, integration: Integration):
+def gen_auth_schema(config: Config, integration: Integration) -> vol.Schema:
     """Generate auth schema."""
     return vol.Schema(
         {
@@ -266,7 +275,7 @@ def gen_auth_schema(config: Config, integration: Integration):
     )
 
 
-def gen_platform_strings_schema(config: Config, integration: Integration):
+def gen_platform_strings_schema(config: Config, integration: Integration) -> vol.Schema:
     """Generate platform strings schema like strings.sensor.json.
 
     Example of valid data:
@@ -279,7 +288,7 @@ def gen_platform_strings_schema(config: Config, integration: Integration):
     }
     """
 
-    def device_class_validator(value):
+    def device_class_validator(value: str) -> str:
         """Key validator for platform states.
 
         Platform states are only allowed to provide states for device classes they prefix.
@@ -313,8 +322,10 @@ ONBOARDING_SCHEMA = vol.Schema({vol.Required("area"): {str: cv.string_with_no_ht
 
 
 def validate_translation_file(  # noqa: C901
-    config: Config, integration: Integration, all_strings
-):
+    config: Config,
+    integration: Integration,
+    all_strings: dict[str, Any] | None,
+) -> None:
     """Validate translation files for integration."""
     if config.specific_integrations:
         check_translations_directory_name(integration)
@@ -326,7 +337,7 @@ def validate_translation_file(  # noqa: C901
         # Only English needs to be always complete
         strings_files.append(integration.path / "translations/en.json")
 
-    references = []
+    references: list[dict[str, str]] = []
 
     if integration.domain == "auth":
         strings_schema = gen_auth_schema(config, integration)
@@ -405,6 +416,9 @@ def validate_translation_file(  # noqa: C901
     if config.specific_integrations:
         return
 
+    if not all_strings:  # Nothing to validate against
+        return
+
     # Validate references
     for reference in references:
         parts = reference["ref"].split("::")
@@ -421,12 +435,12 @@ def validate_translation_file(  # noqa: C901
             )
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Handle JSON files inside integrations."""
     if config.specific_integrations:
         all_strings = None
     else:
-        all_strings = upload.generate_upload_data()
+        all_strings = upload.generate_upload_data()  # type: ignore[no-untyped-call]
 
     for integration in integrations.values():
         validate_translation_file(config, integration, all_strings)
diff --git a/script/hassfest/usb.py b/script/hassfest/usb.py
index 3e5ce6e3963..5420957e201 100644
--- a/script/hassfest/usb.py
+++ b/script/hassfest/usb.py
@@ -5,7 +5,7 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: list[dict[str, str]]) -> str:
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate usb data."""
     match_list = []
 
diff --git a/script/hassfest/zeroconf.py b/script/hassfest/zeroconf.py
index 0c372035bdc..7f8687bded5 100644
--- a/script/hassfest/zeroconf.py
+++ b/script/hassfest/zeroconf.py
@@ -9,10 +9,10 @@ from .model import Config, Integration
 from .serializer import format_python_namespace
 
 
-def generate_and_validate(integrations: dict[str, Integration]):
+def generate_and_validate(integrations: dict[str, Integration]) -> str:
     """Validate and generate zeroconf data."""
     service_type_dict = defaultdict(list)
-    homekit_dict = {}
+    homekit_dict: dict[str, str] = {}
 
     for domain in sorted(integrations):
         integration = integrations[domain]
@@ -77,7 +77,7 @@ def generate_and_validate(integrations: dict[str, Integration]):
     )
 
 
-def validate(integrations: dict[str, Integration], config: Config):
+def validate(integrations: dict[str, Integration], config: Config) -> None:
     """Validate zeroconf file."""
     zeroconf_path = config.root / "homeassistant/generated/zeroconf.py"
     config.cache["zeroconf"] = content = generate_and_validate(integrations)
@@ -96,7 +96,7 @@ def validate(integrations: dict[str, Integration], config: Config):
         return
 
 
-def generate(integrations: dict[str, Integration], config: Config):
+def generate(integrations: dict[str, Integration], config: Config) -> None:
     """Generate zeroconf file."""
     zeroconf_path = config.root / "homeassistant/generated/zeroconf.py"
     with open(str(zeroconf_path), "w") as fp: