diff --git a/api/src/db/schema.ts b/api/src/db/schema.ts
index 922d49f..5907d41 100644
--- a/api/src/db/schema.ts
+++ b/api/src/db/schema.ts
@@ -6,24 +6,24 @@ export const attraction = sqliteTable('attraction', {
     id: integer().primaryKey({ autoIncrement: true }),
     name: text().notNull(),
     apiCode: text('api_code').notNull().unique(),
-    themeparkId: integer('themepark_id').notNull().references(() => themepark.id)
+    themeparkId: integer('themepark_id').notNull().references(() => themepark.id, {onDelete: 'cascade'})
 }, (t) => [
     unique().on(t.apiCode, t.themeparkId)
 ])
 
 export const attractionNotification = sqliteTable('attraction_notification', {
     id: integer().primaryKey({ autoIncrement: true}),
-    userId: integer('user_id').notNull().references(() => user.id),
-    attractionId: integer('attraction_id').notNull().references(() => attraction.id),
-    notificationMethodId: integer('notification_method_id').notNull().references(() => notificationMethod.id)
+    userId: integer('user_id').notNull().references(() => user.id, {onDelete: 'cascade'}),
+    attractionId: integer('attraction_id').notNull().references(() => attraction.id, {onDelete: 'cascade'}),
+    notificationMethodId: integer('notification_method_id').notNull().references(() => notificationMethod.id, {onDelete: 'cascade'})
 }, (t) => [
     unique().on(t.userId, t.attractionId, t.notificationMethodId)
 ])
 
 export const logbook = sqliteTable('logbook', {
     id: integer().primaryKey({ autoIncrement: true }),
-    userId: integer('user_id').notNull().references(() => user.id),
-    attractionId: integer('attraction_id').notNull().references(() => attraction.id),
+    userId: integer('user_id').notNull().references(() => user.id, {onDelete: 'cascade'}),
+    attractionId: integer('attraction_id').notNull().references(() => attraction.id, {onDelete: 'cascade'}),
     timestamp: integer().notNull(), // unix timecode
     expectedWaittime: integer(),
     realWaittime: integer()
@@ -35,8 +35,8 @@ export const notificationMethod = sqliteTable('notification_method', {
     id: integer().primaryKey({ autoIncrement: true }),
     webhookUrl: text('webhook_url').notNull(),
     shownName: text().notNull(),
-    userId: integer('user_id').notNull().references(() => user.id),
-    notificationProviderId: integer('notification_provider_id').notNull().references(() => notificationProvider.id),
+    userId: integer('user_id').notNull().references(() => user.id, {onDelete: 'cascade'}),
+    notificationProviderId: integer('notification_provider_id').notNull().references(() => notificationProvider.id, {onDelete: 'cascade'}),
 }, (t) => [
     unique().on(t.webhookUrl, t.userId, t.notificationProviderId)
 ])
diff --git a/api/src/errors/http-error.ts b/api/src/errors/http-error.ts
index ed9eea3..17d20be 100644
--- a/api/src/errors/http-error.ts
+++ b/api/src/errors/http-error.ts
@@ -28,7 +28,7 @@ export class InvalidParameter extends HTTPException{
         super(400, { message:
             paramName
             ? `Provided parameter '${paramName}' is invalid.`
-            : 'Provided invalid parameter.'
+            : 'Provided invalid request parameter(s) or some required parameter is missing.'
         })
     }
 }
diff --git a/api/src/index.ts b/api/src/index.ts
index b284adf..5d5a858 100644
--- a/api/src/index.ts
+++ b/api/src/index.ts
@@ -6,6 +6,7 @@ import attraction from './routes/attraction'
 import notification from './routes/notification-method'
 import logbook from './routes/logbook'
 import themepark from './routes/themepark'
+import user from './routes/user'
 import cronRouter from './jobs/cron'
 
 // create app
@@ -37,6 +38,7 @@ app.route('/attraction', attraction)
 app.route('/notification-method', notification)
 app.route('/logbook', logbook)
 app.route('/themepark', themepark)
+app.route('/user', user)
 export default {
     fetch: app.fetch,
     scheduled: cronRouter,
diff --git a/api/src/lib/cache.ts b/api/src/lib/cache.ts
index 33124ce..b631337 100644
--- a/api/src/lib/cache.ts
+++ b/api/src/lib/cache.ts
@@ -1,9 +1,17 @@
 import { cache } from 'hono/cache'
 
 /**
- * Cache unit to use for multiple endpoints as needed
+ * Cache unit to use for multiple endpoints as needed (TTL: 86400s)
  */
 export const responseCache = cache({
     cacheName: 'themepark-assistant',
     cacheControl: 'max-age=86400'
+});
+
+/**
+ * Cache for dynamic data (TTL: 30s)
+ */
+export const dynamicCache = cache({
+    cacheName: 'themepark-assistant-dynamic',
+    cacheControl: 'max-age=30s'
 });
\ No newline at end of file
diff --git a/api/src/lib/http-z-validator.ts b/api/src/lib/http-z-validator.ts
index 3308ffe..ee9a787 100644
--- a/api/src/lib/http-z-validator.ts
+++ b/api/src/lib/http-z-validator.ts
@@ -8,8 +8,23 @@ import { InvalidParameter } from '../errors'
  * @param schema Zod Validation scheme (docs: https://zod.dev/api)
  * @returns zValidator for running the validation
  */
-export default function httpZValidator<T extends z.ZodTypeAny>(type: 'query' | 'json' | 'param' = 'query', schema: T){
+export function httpZValidator<T extends z.ZodTypeAny>(type: 'query' | 'json' | 'param' = 'query', schema: T){
     return zValidator(type, schema, (result, c) => {
         if(!result.success) throw new InvalidParameter();
     })
-}
\ No newline at end of file
+}
+
+// Predefined validators
+/**
+ * Validates if id is a number (using zod)
+ */
+export const idValidator = httpZValidator('param', z.strictObject({
+  id: z.coerce.number()
+}));
+
+/**
+ * Validates if notificationMethodId is number (using zod)
+ */
+export const notificationMethodIdValidator = httpZValidator('query', z.strictObject({
+  notificationMethodId: z.coerce.number()
+}));
\ No newline at end of file
diff --git a/api/src/routes/attraction.ts b/api/src/routes/attraction.ts
index a9f2a02..8e95071 100644
--- a/api/src/routes/attraction.ts
+++ b/api/src/routes/attraction.ts
@@ -1,4 +1,4 @@
-import { Hono, Context } from 'hono'
+import { Hono } from 'hono'
 import { getDbContext } from '../db/client'
 import { attractionNotification } from '../db/schema'
 import { and, eq } from 'drizzle-orm'
@@ -6,19 +6,14 @@ import { DatabaseError, InvalidParameter, MissingParameter } from '../errors'
 import { getUser } from '../lib/user-auth'
 import { Message } from '../types/response'
 import { getNotificationMethodOwner } from '../lib/check-notification-method-owner'
+import { httpZValidator, idValidator, notificationMethodIdValidator } from '../lib/http-z-validator'
+import * as z from 'zod'
 
 const app = new Hono()
 
-/**
- * Checks if request has notificationMethodId parameter
- * @param c Request context
- * @returns if available notificationMethodId, else undefined
- */
-function getNotificationMethodId(c: Context): number | undefined{
-    const str = c.req.query('notificationMethodId');
-    if(!str) return undefined;
-    return parseInt(str);
-}
+
+
+
 
 /**
  * Checks if drizzle db error has a message cause
@@ -37,13 +32,12 @@ function hasMessageCause(e: unknown): e is Error & { cause: { message: string }}
 /**
  * Subscribe to waittime notifications from a specified attraction
  */
-app.post('/:id/subscribe', async (c) => {
-    const attractionId = parseInt(c.req.param('id'));
+app.post('/:id/subscribe', idValidator, notificationMethodIdValidator, async (c) => {
+    const attractionId = c.req.valid('param').id;
     const db = getDbContext(c)
     const user = await getUser(c);
 
-    const notificationMethodId = getNotificationMethodId(c);
-    if(!notificationMethodId) throw new MissingParameter('notificationMethodId');
+    const notificationMethodId = c.req.valid('query').notificationMethodId;
 
     const method = await getNotificationMethodOwner(db, notificationMethodId, user.id);
 
@@ -73,12 +67,12 @@ app.post('/:id/subscribe', async (c) => {
 /**
  * Unsubscribe to waittime notifications from a specified attraction
  */
-app.post('/:id/unsubscribe', async (c) => {
-    const attractionId = parseInt(c.req.param('id'));
+app.post('/:id/unsubscribe', idValidator, notificationMethodIdValidator, async (c) => {
+    const attractionId = c.req.valid('param').id;
     const db = getDbContext(c)
     const user = await getUser(c);
 
-    const notificationMethodId = getNotificationMethodId(c);
+    const notificationMethodId = c.req.valid('query').notificationMethodId;
     const methodOwner = notificationMethodId ? await getNotificationMethodOwner(db, notificationMethodId, user.id): false;
 
     const queryConditions = [
diff --git a/api/src/routes/logbook.ts b/api/src/routes/logbook.ts
index fa36f1e..6edf27c 100644
--- a/api/src/routes/logbook.ts
+++ b/api/src/routes/logbook.ts
@@ -1,13 +1,150 @@
 import { Hono } from 'hono'
+import { DatabaseError } from '../errors'
+import { getDbContext } from '../db/client'
+import { logbook } from '../db/schema'
+import { and, eq } from 'drizzle-orm'
+import { getUser } from '../lib/user-auth'
+import { Message } from '../types/response'
+import { httpZValidator } from '../lib/http-z-validator'
+import * as z from 'zod'
 
 const app = new Hono()
 
-app.get('/list', (c) => {
-  return c.json(
-    {
-      message: 'List all logbook entries'
-    }
-  )
+/**
+ * Lists all logbook entries of the logged in user
+ */
+app.get('/list', async (c) => {
+  const db = getDbContext(c);
+  const user = await getUser(c);
+
+  try{
+    const logbookEntries = await db.select({
+      entryId: logbook.id,
+      attractionId: logbook.attractionId,
+      timestamp: logbook.timestamp,
+      expectedWaittime: logbook.expectedWaittime,
+      realWaittime: logbook.realWaittime
+    }).from(logbook)
+    .where(eq(logbook.userId, user.id));
+
+    return c.json(logbookEntries);
+  }
+  catch{
+    throw new DatabaseError();
+  }
+})
+
+/**
+ * Adds new entry to the logbook of the current user
+ */
+app.post('/add-entry', httpZValidator('query', z.strictObject({
+  attractionId: z.coerce.number(),
+  timestamp: z.coerce.number().min(0).positive(),
+  expectedWaittime: z.coerce.number().optional(),
+  realWaittime: z.coerce.number().optional()
+})),
+async (c) => {
+  const db = getDbContext(c);
+  const user = await getUser(c);
+
+  const params = c.req.valid('query');
+
+  try{
+    const res = await db.insert(logbook).values({
+      userId: user.id,
+      attractionId: params.attractionId,
+      timestamp: params.timestamp,
+      expectedWaittime: params.expectedWaittime,
+      realWaittime: params.realWaittime
+    }).onConflictDoNothing().returning();
+
+    const newEntry = res[0];
+
+    const message = res.length > 0
+    ? 'Added new entry to logbook.'
+    : 'Entry already exists. No changes made.';
+
+    return c.json(new Message(message, {
+      entryId: newEntry.id,
+      attractionId: newEntry.attractionId,
+      timestamp: newEntry.timestamp,
+      expectedWaittime: newEntry.expectedWaittime,
+      realWaittime: newEntry.realWaittime
+    }));
+  }
+  catch{
+    throw new DatabaseError();
+  }
+})
+
+/**
+ * Updates waittime information of specified entry (by entryId)
+ */
+app.put('update-entry', httpZValidator('query', z.strictObject({
+  entryId: z.coerce.number(),
+  expectedWaittime: z.coerce.number().optional(),
+  realWaittime: z.coerce.number().optional()
+}).refine((data) => data.expectedWaittime || data.realWaittime)),
+async (c) => {
+  const db = getDbContext(c);
+  const user = await getUser(c);
+  const params = c.req.valid('query');
+
+  try{
+    const res = await db.update(logbook).set({
+      expectedWaittime: params.expectedWaittime,
+      realWaittime: params.realWaittime
+    }).where(and(
+      eq(logbook.userId, user.id),
+      eq(logbook.id, params.entryId)
+    )).returning();
+
+    const modifiedEntry = res[0];
+
+    return c.json(res.length > 0
+      ? new Message('Updated logbook entry.', {
+      entryId: modifiedEntry.id,
+      attractionId: modifiedEntry.attractionId,
+      timestamp: modifiedEntry.timestamp,
+      expectedWaittime: modifiedEntry.expectedWaittime,
+      realWaittime: modifiedEntry.realWaittime
+    })
+    : new Message('Requested entry does not exist. No changes made.')
+    );
+  }
+  catch{
+    throw new DatabaseError();
+  }
+})
+
+/**
+ * Removes specified logbook entry by entryId
+ */
+app.delete('remove-entry', httpZValidator('query', z.strictObject({
+  entryId: z.coerce.number()
+})),
+async (c) => {
+  const db = getDbContext(c);
+  const user = await getUser(c);
+  const params = c.req.valid('query');
+
+  try{
+    const res = await db.delete(logbook).where(
+      and(
+        eq(logbook.userId, user.id),
+        eq(logbook.id, params.entryId)
+      )
+    ).returning();
+
+    const message = res.length > 0
+    ? `Logbook entry with id ${params.entryId} was removed.`
+    : `No logbook entry with id ${params.entryId} found. No changes made.`;
+
+    return c.json(new Message(message));
+  }
+  catch{
+    throw new DatabaseError();
+  }
 })
 
 export default app
\ No newline at end of file
diff --git a/api/src/routes/notification-method.ts b/api/src/routes/notification-method.ts
index 7dde507..a735af3 100644
--- a/api/src/routes/notification-method.ts
+++ b/api/src/routes/notification-method.ts
@@ -5,6 +5,9 @@ import { eq, and } from 'drizzle-orm'
 import { getUser } from '../lib/user-auth'
 import { DatabaseError, InvalidParameter, MissingParameter } from '../errors'
 import { Message } from '../types/response'
+import { responseCache, dynamicCache } from '../lib/cache'
+import { httpZValidator, idValidator } from '../lib/http-z-validator'
+import * as z from 'zod'
 
 const app = new Hono()
 
@@ -51,7 +54,7 @@ app.get('/list', async (c) => {
 })
 
 /** Lists all available notification providers */
-app.get('/list-providers', async (c) => {
+app.get('/list-providers', responseCache, async (c) => {
   const db = getDbContext(c);
 
   try{
@@ -68,21 +71,24 @@ app.get('/list-providers', async (c) => {
 })
 
 /** Creates a new notification method from url, name & provider */
-app.post('/add-method', async (c) => {
+app.post('/add-method', httpZValidator('query', z.strictObject({
+  url: z.string(),
+  name: z.string(),
+  provider: z.string()
+})),
+async (c) => {
   const db = getDbContext(c);
   const user = await getUser(c);
 
-  const { url, name, provider } = c.req.query();
+  const params = c.req.valid('query');
 
-  if(!url || !name || !provider) throw new MissingParameter();
-
-  const providerId = await getProviderId(db, provider);
+  const providerId = await getProviderId(db, params.provider);
   if(!providerId) throw new InvalidParameter('provider');
 
   try{
     const newMethod = await db.insert(notificationMethod).values({
-      webhookUrl: url,
-      shownName: name,
+      webhookUrl: params.url,
+      shownName: params.name,
       userId: user.id,
       notificationProviderId: providerId
     }).returning().onConflictDoNothing().get();
@@ -103,12 +109,10 @@ app.post('/add-method', async (c) => {
 })
 
 /** Removes a existing notification method by id (has to be owned by the current user) */
-app.delete('/remove-method/:id', async (c) => {
+app.delete('/remove-method/:id', idValidator, async (c) => {
   const db = getDbContext(c);
   const user = await getUser(c);
-  const methodId = parseInt(c.req.param('id'));
-
-  if(!methodId) throw new InvalidParameter('id');
+  const methodId = c.req.valid('param').id;
 
   try{
     const res = await db.delete(notificationMethod).where(
diff --git a/api/src/routes/themepark.ts b/api/src/routes/themepark.ts
index 7bd89b9..ae2e7df 100644
--- a/api/src/routes/themepark.ts
+++ b/api/src/routes/themepark.ts
@@ -4,6 +4,7 @@ import { themepark, attraction } from '../db/schema'
 import { responseCache } from '../lib/cache'
 import { eq } from 'drizzle-orm'
 import { DatabaseError } from '../errors'
+import { idValidator } from '../lib/http-z-validator'
 
 const app = new Hono()
 
@@ -30,8 +31,8 @@ app.get('/list', responseCache, async (c) => {
 /**
  * Lists all attractions from a themepark with their id & name
  */
-app.get('/list/:id/attraction', responseCache, async (c) => {
-    const parkId = parseInt(c.req.param('id'));
+app.get('/list/:id/attraction', responseCache, idValidator, async (c) => {
+    const parkId = c.req.valid('param').id;
     const db = getDbContext(c)
 
     try{
diff --git a/api/src/routes/user.ts b/api/src/routes/user.ts
new file mode 100644
index 0000000..a6975a5
--- /dev/null
+++ b/api/src/routes/user.ts
@@ -0,0 +1,44 @@
+import { Hono } from 'hono'
+import { DatabaseError } from '../errors'
+import { getDbContext } from '../db/client'
+import { getUser } from '../lib/user-auth'
+import { user } from '../db/schema'
+import { eq } from 'drizzle-orm'
+import { Message } from '../types/response'
+import { httpZValidator } from '../lib/http-z-validator'
+import * as z from 'zod'
+
+const app = new Hono()
+
+/**
+ * Deletes user account with all associated data (requires parameter 'confirm' to be true)
+ * Be careful when using (once your data is delete it cannot be restored)
+ */
+app.delete('delete-account', httpZValidator('query', z.strictObject({
+  confirm: z.literal('true') // to prevent unwanted account deletion when hitting the endpoint unintentionally
+})),
+async (c) => {
+  const db = getDbContext(c);
+  const currentUser = await getUser(c);
+  const params = c.req.valid('query');
+
+  try{
+    const res = await db.delete(user).where(
+        eq(user.id, currentUser.id)
+    ).returning();
+
+    const deletedUser = res[0];
+
+    const message = res.length > 0
+    ? `User account ${deletedUser.mail} with all associated data deleted.`
+    : 'User account does not exist. No changes made.';
+
+    return c.json(new Message(message));
+  }
+  catch(e){
+    console.error(e);
+    throw new DatabaseError();
+  }
+})
+
+export default app
\ No newline at end of file