diff --git a/client/src/app/features/user/apis/index.ts b/client/src/app/features/user/apis/index.ts
new file mode 100644
index 0000000..bf0c2ec
--- /dev/null
+++ b/client/src/app/features/user/apis/index.ts
@@ -0,0 +1,11 @@
+import { createUserApi } from "./user-api.ts";
+
+const apiBase = import.meta.env.VITE_API_BASE_URL;
+
+if (!apiBase) {
+  throw new Error("VITE_API_BASE_URL is not set");
+}
+
+const userApi = createUserApi({ apiBase });
+
+export const createUser = userApi.createUser;
diff --git a/client/src/app/features/user/apis/user-api.ts b/client/src/app/features/user/apis/user-api.ts
new file mode 100644
index 0000000..414d6d9
--- /dev/null
+++ b/client/src/app/features/user/apis/user-api.ts
@@ -0,0 +1,73 @@
+import type { AgeRange, SubscriptionTier } from "../types";
+
+export type UserApiDeps = {
+  apiBase: string;
+  fetchImpl?: typeof fetch;
+};
+
+export type CreateUserRequest = {
+  first_name: string;
+  last_name: string;
+  email: string;
+  password: string;
+  age_range: AgeRange;
+  subscription_tier: SubscriptionTier;
+  subscription_expires_at: string | null;
+};
+
+export type ApiUserDto = {
+  id: number;
+  first_name: string;
+  last_name: string;
+  email: string;
+  age_range: AgeRange;
+  subscription_tier: SubscriptionTier;
+  subscription_expires_at: string | null;
+};
+
+export type ApiCreateUserResponse =
+  | { status: "success"; data: ApiUserDto }
+  | { status: "error"; data: unknown };
+
+const normalizeApiBase = (apiBase: string): string => apiBase.replace(/\/+$/, "");
+
+export const createUserApi = ({ apiBase, fetchImpl = fetch }: UserApiDeps) => {
+  if (!apiBase) {
+    throw new Error("apiBase is required");
+  }
+
+  const base = normalizeApiBase(apiBase);
+  const endpoint = `${base}/api/v1/users`;
+
+  const withCommonInit = (init?: RequestInit): RequestInit => ({
+    ...init,
+    method: "POST",
+    headers: {
+      Accept: "application/json",
+      "Content-Type": "application/json",
+      ...(init?.headers ?? {}),
+    },
+    credentials: init?.credentials ?? "omit",
+    signal: init?.signal,
+  });
+
+  return {
+    async createUser(request: CreateUserRequest, init?: RequestInit): Promise<ApiUserDto> {
+      const response = await fetchImpl(endpoint, {
+        ...withCommonInit(init),
+        body: JSON.stringify(request),
+      });
+
+      if (!response.ok) {
+        throw new Error(`HTTP ${response.status}`);
+      }
+
+      const json = (await response.json()) as ApiCreateUserResponse;
+      if (json.status !== "success") {
+        throw new Error(`API status is not success: ${json.status}`);
+      }
+
+      return json.data;
+    },
+  };
+};
diff --git a/client/src/app/features/user/types.ts b/client/src/app/features/user/types.ts
new file mode 100644
index 0000000..b708150
--- /dev/null
+++ b/client/src/app/features/user/types.ts
@@ -0,0 +1,15 @@
+export const AGE_RANGES = ["teens", "20s", "30s", "40s", "50s", "60plus"] as const;
+export type AgeRange = (typeof AGE_RANGES)[number];
+
+export const SUBSCRIPTION_TIERS = ["free", "paid"] as const;
+export type SubscriptionTier = (typeof SUBSCRIPTION_TIERS)[number];
+
+export type CreateUserFormValues = {
+  firstName: string;
+  lastName: string;
+  email: string;
+  password: string;
+  ageRange: AgeRange;
+  subscriptionTier: SubscriptionTier;
+  subscriptionExpiresAt: string | null;
+};