diff --git a/backend/package-lock.json b/backend/package-lock.json
index dcf46bd..16845a7 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -8,6 +8,7 @@
       "dependencies": {
         "@prisma/client": "^5.19.1",
         "@prisma/extension-accelerate": "^1.1.0",
+        "@pushkar1713/week13-common": "^1.0.1",
         "hono": "^4.5.11",
         "prisma": "^5.19.1"
       },
@@ -611,6 +612,14 @@
         "@prisma/debug": "5.19.1"
       }
     },
+    "node_modules/@pushkar1713/week13-common": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/@pushkar1713/week13-common/-/week13-common-1.0.1.tgz",
+      "integrity": "sha512-2Ws0BG52cgQtC7trmFdnbOxXwKpw2AQwVBmoa0uwRWfzTFBAAWskpFq71jkTpUEDewfYWjRjCrY7s6ShJm7Uuw==",
+      "dependencies": {
+        "zod": "^3.23.8"
+      }
+    },
     "node_modules/@types/node": {
       "version": "22.5.4",
       "resolved": "https://registry.npmjs.org/@types/node/-/node-22.5.4.tgz",
@@ -1441,7 +1450,6 @@
       "version": "3.23.8",
       "resolved": "https://registry.npmjs.org/zod/-/zod-3.23.8.tgz",
       "integrity": "sha512-XBx9AXhXktjUqnepgTiE5flcKIYWi/rme0Eaj+5Y0lftuGBq+jyRu/md4WnuxqgP1ubdpNCsYEYPxrzVHD8d6g==",
-      "dev": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }
diff --git a/backend/package.json b/backend/package.json
index 6692a8b..740cde8 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -8,6 +8,7 @@
   "dependencies": {
     "@prisma/client": "^5.19.1",
     "@prisma/extension-accelerate": "^1.1.0",
+    "@pushkar1713/week13-common": "^1.0.1",
     "hono": "^4.5.11",
     "prisma": "^5.19.1"
   },
diff --git a/backend/src/routes/posts.ts b/backend/src/routes/posts.ts
index ec0690c..a7a36ea 100644
--- a/backend/src/routes/posts.ts
+++ b/backend/src/routes/posts.ts
@@ -1,7 +1,7 @@
 import { Hono } from "hono";
 import { getPrisma } from "../prismaFunction";
 import { decode, sign, verify } from "hono/jwt";
-
+import { createPost, updatePost } from "@pushkar1713/week13-common";}
 export const postRouter = new Hono<{
   Bindings: {
     DATABASE_URL: string;
@@ -40,6 +40,13 @@ postRouter.use("/*", async (c, next) => {
 postRouter.post("/", async (c) => {
   const prisma = getPrisma(c.env.DATABASE_URL);
   const body = await c.req.json();
+  const { success } = createPost.safeParse(body);
+  if (!success) {
+    c.status(403);
+    return c.json({
+      msg: "invalid types",
+    });
+  }
   const userId = c.get("userId");
 
   const blog = await prisma.post.create({
@@ -84,6 +91,13 @@ postRouter.get("/:id", async (c) => {
 postRouter.put("/", async (c) => {
   const prisma = getPrisma(c.env.DATABASE_URL);
   const body = await c.req.json();
+  const { success } = updatePost.safeParse(body);
+  if (!success) {
+    c.status(403);
+    return c.json({
+      msg: "invalid types",
+    });
+  }
 
   const updatedBlog = await prisma.post.update({
     where: {
diff --git a/backend/src/routes/user.ts b/backend/src/routes/user.ts
index 58421d8..1c00fab 100644
--- a/backend/src/routes/user.ts
+++ b/backend/src/routes/user.ts
@@ -1,6 +1,7 @@
 import { Hono } from "hono";
 import { getPrisma } from "../prismaFunction";
 import { decode, sign, verify } from "hono/jwt";
+import { signinInput, signupInput } from "@pushkar1713/week13-common";
 
 export const userRouter = new Hono<{
   Bindings: {
@@ -12,6 +13,13 @@ export const userRouter = new Hono<{
 userRouter.post("/signup", async (c) => {
   const prisma = getPrisma(c.env.DATABASE_URL);
   const body = await c.req.json();
+  const { success } = signupInput.safeParse(body);
+  if (!success) {
+    c.status(403);
+    return c.json({
+      msg: "invalid types",
+    });
+  }
 
   try {
     const user = await prisma.user.create({
@@ -38,6 +46,13 @@ userRouter.post("/signup", async (c) => {
 userRouter.post("/signin", async (c) => {
   const prisma = getPrisma(c.env.DATABASE_URL);
   const body = await c.req.json();
+  const { success } = signinInput.safeParse(body);
+  if (!success) {
+    c.status(403);
+    return c.json({
+      msg: "invalid types",
+    });
+  }
 
   try {
     const user = prisma.user.findUnique({