diff --git a/app/core/components/ApplicantComments/index.tsx b/app/core/components/ApplicantComments/index.tsx
index 3ad0a1c..e60c34e 100644
--- a/app/core/components/ApplicantComments/index.tsx
+++ b/app/core/components/ApplicantComments/index.tsx
@@ -82,7 +82,7 @@ function CommentItem({
   profileId,
 }: {
   comment: CommentItemType;
-  applicantId: string;
+  applicantId: number;
   profileId: string;
 }) {
   const [openDeleteModal, setOpenDeleteModal] = useState<boolean>(false);
diff --git a/app/models/applicant.server.ts b/app/models/applicant.server.ts
index 3cd729d..f22f246 100644
--- a/app/models/applicant.server.ts
+++ b/app/models/applicant.server.ts
@@ -137,6 +137,14 @@ export async function searchApplicants() {
     .execute();
 }
 
+export async function getApplicantIdByEmail(email: string) {
+  return await db
+    .selectFrom("Applicant as a")
+    .select("id")
+    .where("a.email", "=", email)
+    .executeTakeFirstOrThrow();
+}
+
 export async function getApplicantByEmail(email: string) {
   const applicant = await db
     .selectFrom("Applicant as a")
@@ -158,11 +166,7 @@ export async function getApplicantByEmail(email: string) {
       "m.lastName as mentorLastName",
     ])
     .where("a.email", "=", email)
-    .executeTakeFirst();
-
-  if (!applicant) {
-    return null;
-  }
+    .executeTakeFirstOrThrow();
 
   const projectMembers = await db
     .selectFrom("ProjectMembers")
diff --git a/app/routes/applicants.$applicantId._index.tsx b/app/routes/applicants.$applicantId._index.tsx
index 55eed8b..b1badce 100644
--- a/app/routes/applicants.$applicantId._index.tsx
+++ b/app/routes/applicants.$applicantId._index.tsx
@@ -38,7 +38,7 @@ import ModalBox from "~/core/components/ModalBox";
 import RegularSelect from "~/core/components/RegularSelect";
 import WhatsAppLink from "~/core/components/WhatsAppLink";
 import Header from "~/core/layouts/Header";
-import { getApplicantById } from "~/models/applicant.server";
+import { getApplicantByEmail } from "~/models/applicant.server";
 import { getCommentsApplicant } from "~/models/applicantComment.server";
 import { checkPermission } from "~/models/authorization.server";
 import type { Roles } from "~/models/authorization.server";
@@ -88,12 +88,11 @@ export const validator = withZod(
 );
 
 export const loader = async ({ params, request }: LoaderFunctionArgs) => {
-  invariant(params.applicantId, "projectId not found");
+  invariant(params.applicantId, "applicant not found");
 
   const projects = await getProjectsList();
-  const applicantId = params.applicantId;
-  const comments = await getCommentsApplicant(parseInt(applicantId as string));
-  const applicant = await getApplicantById(params.applicantId);
+  const applicant = await getApplicantByEmail(params.applicantId);
+  const comments = await getCommentsApplicant(applicant.id);
   if (!applicant) {
     throw new Response("Not Found", { status: 404 });
   }
@@ -114,7 +113,7 @@ export const loader = async ({ params, request }: LoaderFunctionArgs) => {
     applicant,
     projects,
     canEditProject,
-    applicantId,
+    applicantId: applicant.id,
     profileId,
     comments,
   });
@@ -191,11 +190,11 @@ export default function Applicant() {
   };
 
   const editApplicant = () => {
-      submit(null, {
+    submit(null, {
       method: "get",
-      action: `/applicationForm/${applicantId}`,
+      action: `/applicationForm/${applicant.email}`,
     });
-  }
+  };
 
   return (
     <>
diff --git a/app/routes/applicants.$applicantId.comment.$id.tsx b/app/routes/applicants.$applicantId.comment.$id.tsx
index 9b3d456..de4c3f4 100644
--- a/app/routes/applicants.$applicantId.comment.$id.tsx
+++ b/app/routes/applicants.$applicantId.comment.$id.tsx
@@ -6,9 +6,8 @@ import { deleteComment, updateComment } from "~/models/applicantComment.server";
 import { getSession } from "~/session.server";
 
 export const action: ActionFunction = async ({ request, params }) => {
-  invariant(params.applicantId, "projectId could not be found");
+  invariant(params.applicantId, "applicant could not be found");
   invariant(params.id, "comment id could not be found");
-  const applicantId = params.applicantId;
   const id = params.id;
 
   try {
@@ -27,5 +26,5 @@ export const action: ActionFunction = async ({ request, params }) => {
     const session = await getSession(request);
     session.flash("warning", "Error while updating comment");
   }
-  return redirect(`/applicants/${applicantId}`);
+  return redirect(`/applicants/${params.applicantId}`);
 };
diff --git a/app/routes/applicants.$applicantId.comment.create.tsx b/app/routes/applicants.$applicantId.comment.create.tsx
index a09889c..bd8bca5 100644
--- a/app/routes/applicants.$applicantId.comment.create.tsx
+++ b/app/routes/applicants.$applicantId.comment.create.tsx
@@ -3,20 +3,21 @@ import { redirect } from "@remix-run/node";
 import { validationError } from "remix-validated-form";
 import invariant from "tiny-invariant";
 import { validator } from "~/core/components/Comments";
+import { getApplicantIdByEmail } from "~/models/applicant.server";
 import { createComment } from "~/models/applicantComment.server";
 import { getSession, requireProfile } from "~/session.server";
 
 export const action: ActionFunction = async ({ request, params }) => {
   invariant(params.applicantId, "applicantId could not be found");
-  const applicantId = params.applicantId;
   const profile = await requireProfile(request);
   const result = await validator.validate(await request.formData());
+  const applicant = await getApplicantIdByEmail(params.applicantId);
 
   if (result.error != undefined) return validationError(result.error);
 
   try {
     await createComment(
-      parseInt(applicantId as string),
+      applicant.id,
       profile.id,
       result.data.body,
       result.data.parentId
@@ -25,5 +26,5 @@ export const action: ActionFunction = async ({ request, params }) => {
     const session = await getSession(request);
     session.flash("warning", "Error while saving comment");
   }
-  return redirect(`/applicants/${applicantId}`);
+  return redirect(`/applicants/${params.applicantId}`);
 };
diff --git a/app/routes/applicants.$applicantId.status.tsx b/app/routes/applicants.$applicantId.status.tsx
index f33cd51..cc08b20 100644
--- a/app/routes/applicants.$applicantId.status.tsx
+++ b/app/routes/applicants.$applicantId.status.tsx
@@ -1,18 +1,18 @@
 /* eslint-disable no-console */
 import type { ActionFunction } from "@remix-run/server-runtime";
 import { redirect } from "remix-typedjson";
-import { editApplicant, getApplicantById } from "~/models/applicant.server";
-import { validator } from "~/routes/applicants.$applicantId._index";
-import { requireProfile, requireUser } from "~/session.server";
 import invariant from "tiny-invariant";
+import { editApplicant, getApplicantByEmail } from "~/models/applicant.server";
 import { checkPermission } from "~/models/authorization.server";
 import type { Roles } from "~/models/authorization.server";
+import { validator } from "~/routes/applicants.$applicantId._index";
+import { requireProfile, requireUser } from "~/session.server";
 
 export const action: ActionFunction = async ({ params, request }) => {
   const profile = await requireProfile(request);
   const user = await requireUser(request);
   invariant(params.applicantId, "applicantId could not be found");
-  const applicant = await getApplicantById(params.applicantId);
+  const applicant = await getApplicantByEmail(params.applicantId);
   if (!applicant) {
     throw new Response("Not Found", { status: 404 });
   }
@@ -27,8 +27,6 @@ export const action: ActionFunction = async ({ params, request }) => {
     throw new Response("Unauthorized", { status: 401 });
   }
 
-
-
   const result = await validator.validate(await request.formData());
   const applicantId = parseInt(result.data?.applicantId as string);
   const status = result.data?.status;
@@ -41,5 +39,7 @@ export const action: ActionFunction = async ({ params, request }) => {
     },
     applicantId
   );
-  return redirect(`/applicants/${response.id}?status=${response.status}`);
+  return redirect(
+    `/applicants/${params.applicantId}?status=${response.status}`
+  );
 };
diff --git a/app/routes/applicationForm.$applicantId._index.tsx b/app/routes/applicationForm.$applicantId._index.tsx
index fbbe642..f3cfb6e 100644
--- a/app/routes/applicationForm.$applicantId._index.tsx
+++ b/app/routes/applicationForm.$applicantId._index.tsx
@@ -130,17 +130,6 @@ function getCurrentDate(): string {
   return `${year}-${month}-${day}`;
 }
 
-interface UserProfile {
-  email: string;
-  name: string;
-}
-
-interface LoaderData {
-  universities: Awaited<ReturnType<typeof getActiveUniversities>>;
-  profile: UserProfile;
-  applicantByEmail: Awaited<ReturnType<typeof getApplicantByEmail>>;
-}
-
 interface UniversityValue {
   id: string;
   name: string;
@@ -156,7 +145,7 @@ export const loader: LoaderFunction = async ({ request }) => {
   const profile = await requireProfile(request);
   const applicantByEmail = await getApplicantByEmail(profile.email);
 
-  return json<LoaderData>({
+  return json({
     universities,
     profile,
     applicantByEmail,
@@ -165,7 +154,7 @@ export const loader: LoaderFunction = async ({ request }) => {
 
 export default function FormPage() {
   const { universities, profile, applicantByEmail } =
-    useLoaderData() as LoaderData;
+    useLoaderData<typeof loader>();
 
   const [selectedUniversity, setSelectedUniversity] =
     useState<UniversityValue | null>({
diff --git a/app/routes/auth.auth0.callback.tsx b/app/routes/auth.auth0.callback.tsx
index 69dc6f5..b00eac9 100644
--- a/app/routes/auth.auth0.callback.tsx
+++ b/app/routes/auth.auth0.callback.tsx
@@ -4,7 +4,6 @@ import { existApplicant } from "~/models/applicant.server";
 import {
   createUserSession,
   getUserRole,
-  requireProfile,
   returnToCookie,
 } from "~/session.server";
 
@@ -23,14 +22,12 @@ export const loader: LoaderFunction = async ({ request, params }) => {
   if (userRole === "ADMIN" || userRole === "USER") {
     roleRedirect = "/projects";
   } else if (userRole === "APPLICANT") {
-    const profile = await requireProfile(request);
-    const checkExistApplicant = await existApplicant(profile.email);
-
+    const checkExistApplicant = await existApplicant(user.email);
     //Check if the user has already answered the "aplicationform".
     if (checkExistApplicant) {
       roleRedirect = "/internshipProjects";
     } else {
-      roleRedirect = `/applicationForm/${profile.id}`;
+      roleRedirect = `/applicationForm/${user.email}`;
     }
   } else {
     roleRedirect = `/login/${params.connection}`;