diff --git a/CHANGELOG.md b/CHANGELOG.md
index c42cd6e..e3eb2e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
+## latest
+
+### Feat
+
+- Support customer App class.
+
 ## v2.0.0b3 (2023-10-26)
 
 ### Fix
diff --git a/idf_build_apps/app.py b/idf_build_apps/app.py
index eb76e4c..a8206bd 100644
--- a/idf_build_apps/app.py
+++ b/idf_build_apps/app.py
@@ -158,9 +158,6 @@ def __init__(
             }
         )
         super().__init__(**kwargs)
-        self._logger = LOGGER.getChild(str(hash(self)))
-        self._logger.addFilter(_AppBuildStageFilter(app=self))
-
         # These internal variables store the paths with environment variables and placeholders;
         # Public properties with similar names use the _expand method to get the actual paths.
         self._work_dir = work_dir or app_dir
@@ -177,8 +174,18 @@ def __init__(
         self._sdkconfig_files = None
         self._sdkconfig_files_defined_target = None
 
+        # create logger and process sdkconfig files
+        self._initialize_hook(**kwargs)
+        self._logger = LOGGER.getChild(str(hash(self)))
+        self._logger.addFilter(_AppBuildStageFilter(app=self))
         self._process_sdkconfig_files()
 
+    def _initialize_hook(self, **kwargs):
+        """
+        Called after variables initialized, before actions such as creating logger.
+        """
+        pass
+
     def __str__(self):
         return '({}) App {}, target {}, sdkconfig {}, build in {}, {} in {}s'.format(
             self.build_system,
diff --git a/idf_build_apps/finder.py b/idf_build_apps/finder.py
index ee483c4..2c15c36 100644
--- a/idf_build_apps/finder.py
+++ b/idf_build_apps/finder.py
@@ -14,7 +14,6 @@
 from .app import (
     App,
     CMakeApp,
-    MakeApp,
 )
 from .constants import (
     BuildStatus,
@@ -29,7 +28,7 @@
 def _get_apps_from_path(
     path: str,
     target: str,
-    build_system: str = 'cmake',
+    app_cls: t.Type[App] = CMakeApp,
     work_dir: t.Optional[str] = None,
     build_dir: str = 'build',
     config_rules_str: t.Union[t.List[str], str, None] = None,
@@ -64,13 +63,6 @@ def _validate_app(_app: App) -> bool:
 
         return True
 
-    if build_system == 'cmake':
-        app_cls = CMakeApp
-    elif build_system == 'make':
-        app_cls = MakeApp
-    else:
-        raise ValueError('Only Support "make" and "cmake"')
-
     if not app_cls.is_app(path):
         LOGGER.debug('Skipping. %s is not an app', path)
         return []
@@ -154,21 +146,21 @@ def _validate_app(_app: App) -> bool:
 def _find_apps(
     path: str,
     target: str,
-    build_system: str = 'cmake',
+    app_cls: t.Type[App] = CMakeApp,
     recursive: bool = False,
     exclude_list: t.Optional[t.List[str]] = None,
     **kwargs,
 ) -> t.List[App]:
     exclude_list = exclude_list or []
     LOGGER.debug(
-        'Looking for %s apps in %s%s with target %s', build_system, path, ' recursively' if recursive else '', target
+        'Looking for %s apps in %s%s with target %s', app_cls.__name__, path, ' recursively' if recursive else '', target
     )
 
     if not recursive:
         if exclude_list:
             LOGGER.warning('--exclude option is ignored when used without --recursive')
 
-        return _get_apps_from_path(path, target, build_system, **kwargs)
+        return _get_apps_from_path(path, target, app_cls, **kwargs)
 
     # The remaining part is for recursive == True
     apps = []
@@ -187,7 +179,7 @@ def _find_apps(
             del dirs[:]
             continue
 
-        _found_apps = _get_apps_from_path(root, target, build_system, **kwargs)
+        _found_apps = _get_apps_from_path(root, target, app_cls, **kwargs)
         if _found_apps:  # root has at least one app
             LOGGER.debug('=> Stop iteration sub dirs of %s since it has apps', root)
             del dirs[:]
diff --git a/idf_build_apps/main.py b/idf_build_apps/main.py
index fa3b9d8..b633049 100644
--- a/idf_build_apps/main.py
+++ b/idf_build_apps/main.py
@@ -18,6 +18,8 @@
 )
 from .app import (
     App,
+    CMakeApp,
+    MakeApp,
 )
 from .build_job import (
     BuildJob,
@@ -84,7 +86,7 @@ def find_apps(
     paths: t.Union[t.List[str], str],
     target: str,
     *,
-    build_system: str = 'cmake',
+    build_system: t.Union[t.Type[App], str] = CMakeApp,
     recursive: bool = False,
     exclude_list: t.Optional[t.List[str]] = None,
     work_dir: t.Optional[str] = None,
@@ -109,7 +111,7 @@ def find_apps(
 
     :param paths: list of app directories (can be / usually will be a relative path)
     :param target: desired value of IDF_TARGET; apps incompatible with the given target are skipped.
-    :param build_system: name of the build system, now only support cmake
+    :param build_system: class of the build system, default CMakeApp
     :param recursive: Recursively search into the nested sub-folders if no app is found or not
     :param exclude_list: list of paths to be excluded from the recursive search
     :param work_dir: directory where the app should be copied before building. Support placeholders
@@ -139,6 +141,16 @@ def find_apps(
         LOGGER.info('Overriding DEFAULT_BUILD_TARGETS to %s', default_build_targets)
         FolderRule.DEFAULT_BUILD_TARGETS = default_build_targets
 
+    if isinstance(build_system, str):
+        # backwards compatible
+        if build_system == 'cmake':
+            build_system = CMakeApp
+        elif build_system == 'make':
+            build_system = MakeApp
+        else:
+            raise ValueError('Only Support "make" and "cmake"')
+    app_cls = build_system
+
     # always set the manifest rootpath at the very beginning of find_apps in case ESP-IDF switches the branch.
     Manifest.ROOTPATH = to_absolute_path(manifest_rootpath or os.curdir)
     Manifest.CHECK_MANIFEST_RULES = check_manifest_rules
@@ -167,7 +179,7 @@ def find_apps(
                 _find_apps(
                     path,
                     target,
-                    build_system,
+                    app_cls,
                     recursive,
                     exclude_list or [],
                     work_dir=work_dir,