diff --git a/lib/types/availability.ts b/lib/types/availability.ts
new file mode 100644
index 0000000..5d3d559
--- /dev/null
+++ b/lib/types/availability.ts
@@ -0,0 +1,14 @@
+export interface AvailabilityResult {
+  domainName: string;
+  available: boolean;
+  rdapStatus: string[] | null;
+}
+
+export interface AvailabilityCheckRequest {
+  domain: string;
+}
+
+export interface AvailabilityCheckResponse {
+  result: AvailabilityResult;
+  queriedAt: string;
+}
diff --git a/lib/types/database.ts b/lib/types/database.ts
new file mode 100644
index 0000000..9724607
--- /dev/null
+++ b/lib/types/database.ts
@@ -0,0 +1,51 @@
+import type { DNSRecord } from "./dns";
+
+export interface Profile {
+  id: string;
+  email: string;
+  displayName: string | null;
+  avatarUrl: string | null;
+  notificationEmail: boolean;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface SavedDomain {
+  id: string;
+  userId: string;
+  domain: string;
+  notes: string | null;
+  tags: string[];
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface DnsHistory {
+  id: string;
+  savedDomainId: string;
+  records: DNSRecord[];
+  checkedAt: string;
+}
+
+export interface AvailabilityHistory {
+  id: string;
+  savedDomainId: string;
+  available: boolean;
+  rdapStatus: string[] | null;
+  checkedAt: string;
+}
+
+export type NotificationType =
+  | "dns_change"
+  | "availability_change"
+  | "expiry_warning";
+
+export interface Notification {
+  id: string;
+  userId: string;
+  savedDomainId: string;
+  type: NotificationType;
+  message: string;
+  read: boolean;
+  createdAt: string;
+}
diff --git a/lib/types/dns.ts b/lib/types/dns.ts
new file mode 100644
index 0000000..77b41f4
--- /dev/null
+++ b/lib/types/dns.ts
@@ -0,0 +1,92 @@
+export interface ARecord {
+  type: "A";
+  address: string;
+}
+
+export interface AAAARecord {
+  type: "AAAA";
+  address: string;
+}
+
+export interface CNAMERecord {
+  type: "CNAME";
+  target: string;
+}
+
+export interface NSRecord {
+  type: "NS";
+  nameserver: string;
+}
+
+export interface MXRecord {
+  type: "MX";
+  priority: number;
+  exchange: string;
+}
+
+export interface TXTRecord {
+  type: "TXT";
+  values: string[];
+}
+
+export interface SOARecord {
+  type: "SOA";
+  nsname: string;
+  hostmaster: string;
+  serial: number;
+  refresh: number;
+  retry: number;
+  expire: number;
+  minttl: number;
+}
+
+export interface CAARecord {
+  type: "CAA";
+  critical: number;
+  iodef?: string;
+  issue?: string;
+  issuewild?: string;
+}
+
+export interface SRVRecord {
+  type: "SRV";
+  priority: number;
+  weight: number;
+  port: number;
+  name: string;
+}
+
+export type DNSRecord =
+  | ARecord
+  | AAAARecord
+  | CNAMERecord
+  | NSRecord
+  | MXRecord
+  | TXTRecord
+  | SOARecord
+  | CAARecord
+  | SRVRecord;
+
+export type DnsRecordType = DNSRecord["type"];
+
+export const DNS_RECORD_DESCRIPTIONS: Record<DnsRecordType, string> = {
+  A: "IPv4 Address",
+  AAAA: "IPv6 Address",
+  CNAME: "Alias Target",
+  NS: "Nameserver",
+  MX: "Mail Server Exchange",
+  TXT: "Text Chunk Array",
+  SOA: "Start of Authority",
+  CAA: "Certificate Authority",
+  SRV: "Service Locator",
+};
+
+export interface DnsLookupRequest {
+  domain: string;
+}
+
+export interface DnsLookupResponse {
+  domain: string;
+  records: DNSRecord[];
+  queriedAt: string; // ISO Timestamp
+}
diff --git a/lib/types/index.ts b/lib/types/index.ts
new file mode 100644
index 0000000..ac86d28
--- /dev/null
+++ b/lib/types/index.ts
@@ -0,0 +1,4 @@
+export * from "./dns";
+export * from "./whois";
+export * from "./availability";
+export * from "./database";
diff --git a/lib/types/whois.ts b/lib/types/whois.ts
new file mode 100644
index 0000000..bfd89e7
--- /dev/null
+++ b/lib/types/whois.ts
@@ -0,0 +1,20 @@
+export interface WhoIsResult {
+  domainName: string;
+  registrar: string | null;
+  createdDate: string | null;
+  updatedDate: string | null;
+  expiresDate: string | null;
+  nameservers: string[];
+  status: string[];
+  dnssec: string | null;
+}
+
+export interface WhoIsLookupRequest {
+  domain: string;
+}
+
+export interface WhoIsLookupResponse {
+  domain: string;
+  result: WhoIsResult;
+  queriedAt: string;
+}