diff --git a/app/config.py b/app/config.py
index 6ad0184..24daa56 100644
--- a/app/config.py
+++ b/app/config.py
@@ -1 +1,35 @@
-"""Typed settings."""
+from functools import lru_cache
+
+from pydantic import Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_prefix="MONITOR_", case_sensitive=False)
+
+    host: str = "0.0.0.0"
+    port: int = Field(8000, ge=1, le=65535)
+    log_level: str = "INFO"
+    default_timeout_seconds: float = Field(5.0, gt=0, le=30)
+    max_timeout_seconds: float = Field(15.0, gt=0, le=60)
+    max_redirects: int = Field(3, ge=0, le=10)
+    allowed_ports: str = "80,443"
+
+    @property
+    def allowed_port_set(self) -> frozenset[int]:
+        try:
+            ports = frozenset(int(value.strip()) for value in self.allowed_ports.split(","))
+        except ValueError as exc:
+            raise ValueError("MONITOR_ALLOWED_PORTS must be comma-separated integers") from exc
+        if not ports or any(port < 1 or port > 65535 for port in ports):
+            raise ValueError("MONITOR_ALLOWED_PORTS contains an invalid port")
+        return ports
+
+
+@lru_cache
+def get_settings() -> Settings:
+    settings = Settings()
+    settings.allowed_port_set
+    if settings.default_timeout_seconds > settings.max_timeout_seconds:
+        raise ValueError("default timeout cannot exceed maximum timeout")
+    return settings