diff --git a/concord-server/src/routes/userRoutes.ts b/concord-server/src/routes/userRoutes.ts
index 3d507a1..4fc91f3 100644
--- a/concord-server/src/routes/userRoutes.ts
+++ b/concord-server/src/routes/userRoutes.ts
@@ -1,33 +1,67 @@
 import { Hono } from "hono";
 import { fetchAllUsers, fetchUserData, createNewUser } from "../controller/userController";
-import { createUserSchema } from "../validators/userValidator";
+import { createUserSchema, queryAllUsersByInstanceId, queryUserByIdSchema } from "../validators/userValidator";
 import { zValidator } from "@hono/zod-validator";
 import { describeRoute, resolver } from "hono-openapi";
 const actions = new Hono();
 
-actions.get("user/:id", async (c) => {
-  const id = c.req.param("id");
-  const userData = await fetchUserData(id);
-  if (userData) {
-    return c.json(userData);
-  } else {
-    return c.json({ error: "User not found" }, 404);
+actions.get("user/:id", 
+  describeRoute({
+    description: "Get user by id",
+    responses: {
+      200: {
+        description: "Success getting user",
+        content: {
+          "application/json": { schema: resolver(queryUserByIdSchema) }
+        }
+      },
+      404: {
+        description: "User id not found",
+        content: {
+          "application/json": { schema: resolver(queryUserByIdSchema) }
+        }
+      }
+    }
+  }),
+  zValidator('param', queryUserByIdSchema),
+  async (c) => {
+    const id = c.req.param("id");
+    const userData = await fetchUserData(id);
+    if (userData) {
+      return c.json(userData);
+    } else {
+      return c.json({ error: "User not found" }, 404);
+    }
   }
-});
+);
 
-actions.get("user", async (c) => {
-  const instanceId = c.req.query("instance_id");
-  if (!instanceId) {
-    return c.json({ error: "No instance id provided" }, 400);
-  }
+actions.get("user",
+  describeRoute({
+    description: "Get all users by instance id",
+    responses: {
+      200: {
+        description: "Success getting all users in instance",
+        content: {
+          "application/json": { schema: resolver(queryAllUsersByInstanceId) }
+        }
+      }
+    }
+  }),
+  zValidator('query', queryAllUsersByInstanceId),
+  async (c) => {
+    const instanceId = c.req.query("instanceId");
+    if (!instanceId) {
+      return c.json({ error: "No instance id provided" }, 400);
+    }
 
-  const userData = await fetchAllUsers(instanceId);
-  if (userData) {
-    return c.json(userData);
-  } else {
-    return c.json({ error: "Error getting all users from instance" }, 500);
+    const userData = await fetchAllUsers(instanceId);
+    if (userData) {
+      return c.json(userData);
+    } else {
+      return c.json({ error: "Error getting all users from instance" }, 500);
+    }
   }
-});
+);
 
 actions.post(
   "user",
@@ -39,6 +73,12 @@ actions.post(
         content: {
           'application/json': { schema: resolver(createUserSchema) },
         },
+      },
+      400: {
+        description: "Bad request (user exists)",
+        content: {
+          'application/json': { schema: resolver(createUserSchema) }
+        }
       }
     }
   }),
@@ -47,6 +87,9 @@ actions.post(
     try {
       const data = await c.req.json();
       const newUser = await createNewUser(data);
+      if (!newUser) {
+        return c.json({ error: "User already exists" }, 400);
+      }
       return c.json(newUser, 201);
     } catch (error) {
       return c.json({ error: "Error creating user" }, 500);
diff --git a/concord-server/src/services/userService.ts b/concord-server/src/services/userService.ts
index 23f19dd..4228b66 100644
--- a/concord-server/src/services/userService.ts
+++ b/concord-server/src/services/userService.ts
@@ -10,6 +10,10 @@ import { CreateUserInput } from '../validators/userValidator';
 const prisma = new PrismaClient();
 
 export async function createUser(data: CreateUserInput) {
+  if (await prisma.user.count({ where: { username: data.username }}) >= 1) {
+    return null;
+  }
+
   return await prisma.user.create({
     data: {
       username: data.username,
@@ -111,9 +115,13 @@ export async function getAllUsersFrom(instanceId: string): Promise<
   | null
 > {
   try {
-    const instances = await prisma.instance.findMany();
-    if (!instances) {
-      throw new Error("could not get all instances");
+    const instances = await prisma.instance.count({
+      where: {
+        id: instanceId
+      }
+    })
+    if (instances < 1) {
+      throw new Error("could not find given instance id");
     }
 
     const users = await prisma.user.findMany({
diff --git a/concord-server/src/validators/userValidator.ts b/concord-server/src/validators/userValidator.ts
index 0f7eae6..a4aaa60 100644
--- a/concord-server/src/validators/userValidator.ts
+++ b/concord-server/src/validators/userValidator.ts
@@ -1,5 +1,13 @@
 import { z } from 'zod'
 
+export const queryUserByIdSchema = z.object({
+  id: z.uuidv7()
+})
+
+export const queryAllUsersByInstanceId = z.object({
+  instanceId: z.uuidv7()
+})
+
 export const createUserSchema = z.object({
   username: z.string().min(3).max(30),
   nickname: z.string().min(1).max(30).optional(),