diff --git a/src/constants/url.ts b/src/constants/url.ts
new file mode 100644
index 0000000..7edc2c2
--- /dev/null
+++ b/src/constants/url.ts
@@ -0,0 +1,2 @@
+export const VALID_URL_REGEX =
+  /^(?:http(s)?:\/\/)[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~:/?#[\]@!\$&'\(\)\*\+,;=.\%]+$/;
diff --git a/src/pages/index.tsx b/src/pages/index.tsx
index 6ec8d81..490568d 100644
--- a/src/pages/index.tsx
+++ b/src/pages/index.tsx
@@ -13,10 +13,10 @@ import PATHS from "constants/paths";
 import useModal from "hooks/useModal";
 import { Category, Link, SearchItem } from "types";
 
-import { BuildCategory } from "utils/front";
+import getUserCategories from "lib/category/getUserCategories";
+import getUser from "lib/user/getUser";
 import { pushStateVanilla } from "utils/link";
-import prisma from "utils/prisma";
-import { getSessionOrThrow } from "utils/session";
+import { getSession } from "utils/session";
 
 interface HomePageProps {
   categories: Category[];
@@ -187,29 +187,12 @@ function Home(props: HomePageProps) {
 }
 
 export async function getServerSideProps({ req, res, query }) {
-  const session = await getSessionOrThrow(req, res);
+  const session = await getSession(req, res);
   const queryCategoryId = (query?.categoryId as string) || "";
 
-  const user = await prisma.user.findFirstOrThrow({
-    where: {
-      email: session.user.email,
-    },
-  });
-  const categoriesDB = await prisma.category.findMany({
-    include: {
-      links: {
-        where: {
-          authorId: user.id,
-        },
-      },
-      author: true,
-    },
-    where: {
-      authorId: user.id,
-    },
-  });
-
-  if (categoriesDB.length === 0) {
+  const user = await getUser(session);
+  const categories = await getUserCategories(user);
+  if (categories.length === 0) {
     return {
       redirect: {
         destination: PATHS.CATEGORY.CREATE,
@@ -217,11 +200,9 @@ export async function getServerSideProps({ req, res, query }) {
     };
   }
 
-  const categories = categoriesDB.map(BuildCategory);
   const currentCategory = categories.find(
     ({ id }) => id === Number(queryCategoryId)
   );
-
   return {
     props: {
       categories: JSON.parse(JSON.stringify(categories)),
diff --git a/src/pages/link/create.tsx b/src/pages/link/create.tsx
index 7694ee2..aceda9e 100644
--- a/src/pages/link/create.tsx
+++ b/src/pages/link/create.tsx
@@ -10,9 +10,11 @@ import Selector from "components/Selector";
 import TextBox from "components/TextBox";
 
 import useAutoFocus from "hooks/useAutoFocus";
+import getUserCategories from "lib/category/getUserCategories";
+import getUser from "lib/user/getUser";
 import { Category, Link } from "types";
-import { BuildCategory, HandleAxiosError, IsValidURL } from "utils/front";
-import prisma from "utils/prisma";
+import { HandleAxiosError, IsValidURL } from "utils/front";
+import { getSession } from "utils/session";
 
 import styles from "styles/create.module.scss";
 
@@ -110,14 +112,11 @@ function CreateLink({ categories }: { categories: Category[] }) {
 CreateLink.authRequired = true;
 export default CreateLink;
 
-export async function getServerSideProps() {
-  const categoriesDB = await prisma.category.findMany({
-    include: { author: true },
-  });
-  const categories = categoriesDB.map((categoryDB) =>
-    BuildCategory(categoryDB)
-  );
+export async function getServerSideProps({ req, res }) {
+  const session = await getSession(req, res);
+  const user = await getUser(session);
 
+  const categories = await getUserCategories(user);
   if (categories.length === 0) {
     return {
       redirect: {
diff --git a/src/pages/link/remove/[lid].tsx b/src/pages/link/remove/[lid].tsx
index 481e303..6fe10a5 100644
--- a/src/pages/link/remove/[lid].tsx
+++ b/src/pages/link/remove/[lid].tsx
@@ -8,9 +8,11 @@ import FormLayout from "components/FormLayout";
 import PageTransition from "components/PageTransition";
 import TextBox from "components/TextBox";
 
+import getUserLink from "lib/link/getUserLink";
+import getUser from "lib/user/getUser";
 import { Link } from "types";
-import { BuildLink, HandleAxiosError } from "utils/front";
-import prisma from "utils/prisma";
+import { HandleAxiosError } from "utils/front";
+import { getSession } from "utils/session";
 
 import styles from "styles/create.module.scss";
 
@@ -94,14 +96,14 @@ function RemoveLink({ link }: { link: Link }) {
 RemoveLink.authRequired = true;
 export default RemoveLink;
 
-export async function getServerSideProps({ query }) {
+export async function getServerSideProps({ req, res, query }) {
   const { lid } = query;
-  const linkDB = await prisma.link.findFirst({
-    where: { id: Number(lid) },
-    include: { category: true, author: true },
-  });
 
-  if (!linkDB) {
+  const session = await getSession(req, res);
+  const user = await getUser(session);
+
+  const link = await getUserLink(user, Number(lid));
+  if (!link) {
     return {
       redirect: {
         destination: "/",
@@ -109,10 +111,6 @@ export async function getServerSideProps({ query }) {
     };
   }
 
-  const link = BuildLink(linkDB, {
-    categoryId: linkDB.categoryId,
-    categoryName: linkDB.category.name,
-  });
   return {
     props: {
       link: JSON.parse(JSON.stringify(link)),
diff --git a/src/pages/signin.tsx b/src/pages/signin.tsx
index 54dd4f7..44e3aef 100644
--- a/src/pages/signin.tsx
+++ b/src/pages/signin.tsx
@@ -1,4 +1,3 @@
-import { getServerSession } from "next-auth/next";
 import { Provider } from "next-auth/providers";
 import { getProviders, signIn } from "next-auth/react";
 import { NextSeo } from "next-seo";
@@ -6,9 +5,9 @@ import Link from "next/link";
 
 import MessageManager from "components/MessageManager/MessageManager";
 import PATHS from "constants/paths";
+import { getSession } from "utils/session";
 
 import styles from "styles/login.module.scss";
-import { authOptions } from "./api/auth/[...nextauth]";
 
 interface SignInProps {
   providers: Provider[];
@@ -39,7 +38,7 @@ export default function SignIn({ providers }: SignInProps) {
 }
 
 export async function getServerSideProps({ req, res }) {
-  const session = await getServerSession(req, res, authOptions);
+  const session = await getSession(req, res);
   if (session) {
     return {
       redirect: {
diff --git a/src/types.d.ts b/src/types.d.ts
index b8e8a38..b561a77 100644
--- a/src/types.d.ts
+++ b/src/types.d.ts
@@ -1,5 +1,7 @@
 import { User } from "@prisma/client";
 
+// TODO: extend @prisma/client type with Link[] instead of
+// recreate interface (same for Link)
 export interface Category {
   id: number;
   name: string;
diff --git a/src/utils/front.ts b/src/utils/front.ts
index 00dc492..ff5fd25 100644
--- a/src/utils/front.ts
+++ b/src/utils/front.ts
@@ -1,53 +1,8 @@
 import axios from "axios";
-
-import { Category, Link } from "types";
-
-export function BuildCategory({
-  id,
-  name,
-  authorId,
-  author,
-  links = [],
-  createdAt,
-  updatedAt,
-}): Category {
-  return {
-    id,
-    name,
-    links: links.map((link) =>
-      BuildLink(link, { categoryId: id, categoryName: name })
-    ),
-    authorId,
-    author,
-    createdAt,
-    updatedAt,
-  };
-}
-
-export function BuildLink(
-  { id, name, url, authorId, author, favorite, createdAt, updatedAt },
-  { categoryId, categoryName }
-): Link {
-  return {
-    id,
-    name,
-    url,
-    category: {
-      id: categoryId,
-      name: categoryName,
-    },
-    authorId,
-    author,
-    favorite,
-    createdAt,
-    updatedAt,
-  };
-}
+import { VALID_URL_REGEX } from "constants/url";
 
 export function IsValidURL(url: string): boolean {
-  const regex = new RegExp(
-    /^(?:http(s)?:\/\/)[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~:/?#[\]@!\$&'\(\)\*\+,;=.\%]+$/
-  );
+  const regex = new RegExp(VALID_URL_REGEX);
   return url.match(regex) ? true : false;
 }