diff --git a/vollerei/common/api/resource.py b/vollerei/common/api/resource.py
new file mode 100644
index 0000000..8488a8f
--- /dev/null
+++ b/vollerei/common/api/resource.py
@@ -0,0 +1,178 @@
+"""
+Class wrapper for API endpoint /resource
+"""
+
+
+class Segment:
+    path: str
+    md5: str
+    # str -> int and checked if int is 0 then None
+    package_size: int | None
+
+
+class VoicePack:
+    """
+    Voice pack information
+
+    `name` maybe converted from `path` if the server returns empty string.
+
+    Attributes:
+        TODO
+    """
+
+    language: str
+    name: str
+    path: str
+    # str -> int
+    size: int
+    md5: str
+    # str -> int
+    package_size: int
+
+
+class Diff:
+    """
+    Game resource diff from a version to latest information
+
+    Attributes:
+        TODO
+    """
+
+    name: str
+    version: str
+    path: str
+    # str -> int
+    size: int
+    md5: str
+    is_recommended_update: bool
+    voice_packs: list[VoicePack]
+    # str -> int
+    package_size: int
+
+
+class Latest:
+    """
+    Latest game resource information
+
+    `name` maybe converted from `path` if the server returns empty string,
+    and if `path` is empty too then it'll convert the name from the first
+    segment of `segments` list.
+
+    Attributes:
+        TODO
+    """
+
+    name: str
+    version: str
+    path: str
+    # str -> int
+    size: int
+    md5: str
+    entry: str
+    voice_packs: list[VoicePack]
+    # str but checked for empty string
+    decompressed_path: str | None
+    segments: list[Segment]
+    # str -> int
+    package_size: int
+
+    def __init__(
+        self,
+        name: str,
+        version: str,
+        path: str,
+        size: int,
+        md5: str,
+        entry: str,
+        voice_packs: list[VoicePack],
+        decompressed_path: str | None,
+        segments: list[Segment],
+        package_size: int,
+    ) -> None:
+        self.name = name
+        self.version = version
+        self.path = path
+        self.size = size
+        self.md5 = md5
+        self.entry = entry
+        self.voice_packs = voice_packs
+        self.decompressed_path = decompressed_path
+        self.segments = segments
+        self.package_size = package_size
+
+
+class Game:
+    latest: Latest
+    diffs: list[Diff]
+
+
+class Plugin:
+    name: str
+    # str but checked for empty string
+    version: str | None
+    path: str
+    # str -> int
+    size: int
+    md5: str
+    # str but checked for empty string
+    entry: str | None
+    # str -> int
+    package_size: int
+
+
+class LauncherPlugin:
+    plugins: list[Plugin]
+    # str -> int
+    version: int
+
+
+class DeprecatedPackage:
+    name: str
+    md5: str
+
+
+class DeprecatedFile:
+    path: str
+    # str but checked for empty string
+    md5: str | None
+
+
+class Data:
+    """
+    Data class for /resource endpoint
+    """
+
+    # I'm generous enough to convert the string into int
+    # for you guys, wtf Mihoyo?
+    game: Game
+    # ?? Mihoyo for plugin["plugins"] which is a list of Plugin objects
+    plugin: LauncherPlugin
+    web_url: str
+    # ?? Mihoyo
+    force_update: None
+    # Will be a Game object if a pre-download is available.
+    pre_download_game: Game | None
+    deprecated_packages: list[DeprecatedPackage]
+    # Maybe a SDK for Bilibili version in Genshin?
+    sdk: None
+    deprecated_files: list[DeprecatedFile]
+
+    def __init__(
+        self,
+        game: Game,
+        plugin: Plugin,
+        web_url: str,
+        force_update: None,
+        pre_download_game: Game | None,
+        deprecated_packages: list[DeprecatedPackage],
+        sdk: None,
+        deprecated_files: list[DeprecatedFile],
+    ) -> None:
+        self.game = game
+        self.plugin = plugin
+        self.web_url = web_url
+        self.force_update = force_update
+        self.pre_download_game = pre_download_game
+        self.deprecated_packages = deprecated_packages
+        self.sdk = sdk
+        self.deprecated_files = deprecated_files
diff --git a/vollerei/hsr/constants.py b/vollerei/hsr/constants.py
index 317752e..5a515b1 100644
--- a/vollerei/hsr/constants.py
+++ b/vollerei/hsr/constants.py
@@ -1,3 +1,25 @@
+class LAUNCHER_API:
+    """Launcher API constants."""
+
+    RESOURCE_PATH: str = "mdk/launcher/api/resource"
+    OS: dict = {
+        "url": "https://hkrpg-launcher-static.hoyoverse.com/hkrpg_global/",
+        "params": {
+            "channel_id": 1,
+            "key": "vplOVX8Vn7cwG8yb",
+            "launcher_id": 35,
+        },
+    }
+    CN: dict = {
+        "url": "https://api-launcher.mihoyo.com/hkrpg_cn/mdk/launcher/api/resource",
+        "params": {
+            "channel_id": 1,
+            "key": "6KcVuOkbcqjJomjZ",
+            "launcher_id": 33,
+        },
+    }
+
+
 LATEST_VERSION = (1, 1, 0)
 MD5SUMS = {
     "1.0.5": {
diff --git a/vollerei/hsr/launcher/api.py b/vollerei/hsr/launcher/api.py
new file mode 100644
index 0000000..e69de29