diff --git a/src/lib/whois.ts b/src/lib/whois.ts
index f04956f..503d675 100644
--- a/src/lib/whois.ts
+++ b/src/lib/whois.ts
@@ -1,15 +1,38 @@
+import type {
+  WhoIsResponse,
+  WhoIsData,
+  WhoIsEvent,
+  WhoIsIpAddresses,
+} from "@/types";
+
+function checkEvents(events: WhoIsEvent[]): boolean {
+  for (const event of events) {
+    if (event.eventAction === "registration" && event.eventDate === "") {
+      return true;
+    }
+  }
+  return false;
+}
+
+function checkIpAddresses(ipAddresses: WhoIsIpAddresses): boolean {
+  return ipAddresses.v4.length === 0 && ipAddresses.v6.length === 0;
+}
+
+function checkWhoIsData(data: WhoIsData): boolean {
+  return (
+    checkEvents(data.events) &&
+    checkIpAddresses(data.ipAddresses) &&
+    data.nameservers.length === 0
+  );
+}
+
 export async function isDomainAvailable(domain: string): Promise<boolean> {
   try {
     const response = await fetch(
       `https://whois.klemek.fr/api/lookup/${domain}`,
     );
-    const content = await response.json();
-    for (const event of content?.data?.events ?? []) {
-      if (event?.eventAction === "registration" && event?.eventDate === "") {
-        return true;
-      }
-    }
-    return false;
+    const content: WhoIsResponse = await response.json();
+    return checkWhoIsData(content.data);
   } catch {
     return false;
   }
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 0000000..e7136e3
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,33 @@
+export interface WhoIsResponse {
+  type: string;
+  data: WhoIsData;
+}
+
+export interface WhoIsData {
+  ldhName: string;
+  handle: string;
+  status: string[];
+  ipAddresses: WhoIsIpAddresses;
+  events: WhoIsEvent[];
+  nameservers: WhoIsNameserver[];
+  entities: WhoIsEntity[];
+}
+
+export interface WhoIsIpAddresses {
+  v4: string[];
+  v6: string[];
+}
+
+export interface WhoIsEvent {
+  eventAction: string;
+  eventDate: string;
+}
+
+export interface WhoIsNameserver {
+  ldhName: string;
+}
+
+export interface WhoIsEntity {
+  roles: string[];
+  vcardArray: [string, [string, object, string, string][]];
+}