diff --git a/parts/4/blogApp/package.json b/parts/4/blogApp/package.json
index 66dab5e..46a1109 100644
--- a/parts/4/blogApp/package.json
+++ b/parts/4/blogApp/package.json
@@ -5,7 +5,7 @@
   "scripts": {
     "start": "node src/app.js",
     "dev": "node --watch src/app.js",
-    "test": "node --test"
+    "test": "echo \"Error: no test specified\" && exit 1"
   },
   "author": "",
   "license": "ISC",
diff --git a/parts/4/blogApp/src/app.js b/parts/4/blogApp/src/app.js
index b1bb5ca..170b6ad 100644
--- a/parts/4/blogApp/src/app.js
+++ b/parts/4/blogApp/src/app.js
@@ -1,12 +1,37 @@
-const express = require("express");
-const { addRoutes } = require("./routes");
-const app = express();
+const express = require('express')
+const mongoose = require('mongoose')
 
-app.use(express.json());
+const app = express()
 
-addRoutes(app);
+const blogSchema = mongoose.Schema({
+  title: String,
+  author: String,
+  url: String,
+  likes: Number,
+})
 
-const PORT = 3003;
+const Blog = mongoose.model('Blog', blogSchema)
+
+const mongoUrl = 'mongodb://localhost/bloglist'
+mongoose.connect(mongoUrl)
+
+app.use(express.json())
+
+app.get('/api/blogs', (request, response) => {
+  Blog.find({}).then((blogs) => {
+    response.json(blogs)
+  })
+})
+
+app.post('/api/blogs', (request, response) => {
+  const blog = new Blog(request.body)
+
+  blog.save().then((result) => {
+    response.status(201).json(result)
+  })
+})
+
+const PORT = 3003
 app.listen(PORT, () => {
-  console.log(`Server running on port ${PORT}`);
-});
+  console.log(`Server running on port ${PORT}`)
+})
\ No newline at end of file
diff --git a/parts/4/blogApp/src/db.js b/parts/4/blogApp/src/db.js
deleted file mode 100644
index 5456522..0000000
--- a/parts/4/blogApp/src/db.js
+++ /dev/null
@@ -1,15 +0,0 @@
-const mongoose = require('mongoose')
-
-const blogSchema = mongoose.Schema({
-  title: String,
-  author: String,
-  url: String,
-  likes: Number,
-})
-
-const Blog = mongoose.model('Blog', blogSchema)
-
-const mongoUrl = 'mongodb://localhost/bloglist'
-mongoose.connect(mongoUrl)
-
-module.exports = {models: {Blog}}
\ No newline at end of file
diff --git a/parts/4/blogApp/src/routes.js b/parts/4/blogApp/src/routes.js
deleted file mode 100644
index 7225b3a..0000000
--- a/parts/4/blogApp/src/routes.js
+++ /dev/null
@@ -1,22 +0,0 @@
-const { models } = require("./db");
-const Blog = models.Blog;
-
-BASE_API_PATH = "/api";
-
-const addRoutes = (app) => {
-  app.get(`${BASE_API_PATH}/blogs`, (request, response) => {
-    Blog.find({}).then((blogs) => {
-      response.json(blogs);
-    });
-  });
-
-  app.post(`${BASE_API_PATH}/blogs`, (request, response) => {
-    const blog = new Blog(request.body);
-
-    blog.save().then((result) => {
-      response.status(201).json(result);
-    });
-  });
-};
-
-module.exports = { addRoutes };
diff --git a/parts/4/blogApp/src/utils.js b/parts/4/blogApp/src/utils.js
deleted file mode 100644
index 9653c37..0000000
--- a/parts/4/blogApp/src/utils.js
+++ /dev/null
@@ -1,89 +0,0 @@
-const reverse = (string) => {
-  return string.split("").reverse().join("");
-};
-
-const average = (array) => {
-  const reducer = (sum, item) => {
-    return sum + item;
-  };
-
-  return array.length === 0 ? 0 : array.reduce(reducer, 0) / array.length;
-};
-
-const listHelper = (posts) => {
-  console.log("lol");
-  return 1;
-};
-
-const totalLikes = (posts) => {
-  if (!posts) {
-    return 0;
-  }
-
-  const likeCount = posts
-    .map((post) => post.likes)
-    .reduce((cum, value) => cum + value, 0);
-
-  return likeCount;
-};
-
-const favoritePost = (posts) => {
-  if (!posts || posts.length === 0) {
-    return null;
-  }
-
-  const highestLikes = posts.reduce(
-    (max, post) => (post.likes > max ? (max = post.likes) : max),
-    0
-  );
-
-  const favoritePost = posts.find((post) => post.likes == highestLikes);
-
-  return favoritePost;
-};
-
-const mostPosts = (posts) => {
-  if (!posts || posts.length === 0) {
-    return null;
-  }
-
-  const countMap = posts.reduce((acc, post) => {
-    acc[post.author] = (acc[post.author] || 0) + 1;
-    return acc;
-  }, {});
-
-  const [author, postsCount] = Object.entries(countMap).reduce(
-    (max, entry) => (entry[1] > max[1] ? entry : max),
-    ['', 0]
-  );
-
-  return { author, posts: postsCount };
-};
-
-const mostLikes = (posts) => {
-    if (!posts || posts.length === 0) {
-      return null;
-    }
-  
-    const likesMap = posts.reduce((acc, post) => {
-      acc[post.author] = (acc[post.author] || 0) + post.likes;
-      return acc;
-    }, {});
-  
-    const [author, likesCount] = Object.entries(likesMap).reduce(
-      (max, entry) => (entry[1] > max[1] ? entry : max),
-      ['', 0]
-    );
-  
-    return { author, likes: likesCount };
-  };
-
-module.exports = {
-  reverse,
-  average,
-  listHelper,
-  totalLikes,
-  favoritePost,
-  mostPosts,
-  mostLikes
-};
diff --git a/parts/4/blogApp/tests/average.test.js b/parts/4/blogApp/tests/average.test.js
deleted file mode 100644
index a7f56f5..0000000
--- a/parts/4/blogApp/tests/average.test.js
+++ /dev/null
@@ -1,18 +0,0 @@
-const { test, describe } = require('node:test')
-const assert = require('node:assert')
-
-const average = require('../src/utils').average
-
-describe('average', () => {
-  test('of one value is the value itself', () => {
-    assert.strictEqual(average([1]), 1)
-  })
-
-  test('of many is calculated right', () => {
-    assert.strictEqual(average([1, 2, 3, 4, 5, 6]), 3.5)
-  })
-
-  test('of empty array is zero', () => {
-    assert.strictEqual(average([]), 0)
-  })
-})
\ No newline at end of file
diff --git a/parts/4/blogApp/tests/favoritePost.test.js b/parts/4/blogApp/tests/favoritePost.test.js
deleted file mode 100644
index d452e35..0000000
--- a/parts/4/blogApp/tests/favoritePost.test.js
+++ /dev/null
@@ -1,43 +0,0 @@
-const { test, describe } = require("node:test");
-const assert = require("node:assert");
-const { favoritePost } = require("../src/utils");
-
-describe("favoritePost ", () => {
-  const posts = [
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 5,
-      __v: 0,
-    },
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 2,
-      __v: 0,
-    },
-  ];
-
-  const emptyArray = [];
-
-  const gibberish = "asdaSd123asd";
-
-  test("finds top properly", () => {
-    assert.strictEqual(favoritePost(posts), posts[0]);
-  });
-
-  test("works fine with empty array", () => {
-    assert.strictEqual(favoritePost(emptyArray), null);
-  });
-
-  test("fails with gibberish input", () => {
-    const failedCall = () => {
-      favoritePost(gibberish);
-    };
-    assert.throws(failedCall, Error);
-  });
-});
diff --git a/parts/4/blogApp/tests/listHelper.test.js b/parts/4/blogApp/tests/listHelper.test.js
deleted file mode 100644
index b7b6881..0000000
--- a/parts/4/blogApp/tests/listHelper.test.js
+++ /dev/null
@@ -1,10 +0,0 @@
-const { test, describe } = require("node:test");
-const assert = require("node:assert");
-const { listHelper } = require("../src/utils");
-
-test("dummy returns one", () => {
-  const blogs = [];
-
-  const result = listHelper(blogs);
-  assert.strictEqual(result, 1);
-});
diff --git a/parts/4/blogApp/tests/mostLikes.test.js b/parts/4/blogApp/tests/mostLikes.test.js
deleted file mode 100644
index 2977375..0000000
--- a/parts/4/blogApp/tests/mostLikes.test.js
+++ /dev/null
@@ -1,54 +0,0 @@
-const { test, describe } = require("node:test");
-const assert = require("node:assert");
-const { mostLikes } = require("../src/utils");
-
-describe("most likes ", () => {
-  const posts = [
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 5,
-      __v: 0,
-    },
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 2,
-      __v: 0,
-    },
-    {
-      _id: "123",
-      title: "Lololo",
-      author: "John Doe",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 1,
-      __v: 0,
-    },
-  ];
-
-  const emptyArray = [];
-
-  const gibberish = "asdaSd123asd";
-
-  test("finds top author  properly", () => {
-    assert.deepStrictEqual(mostLikes(posts), {
-      author: "Edsger W. Dijkstra",
-      likes: 7,
-    });
-  });
-
-  test("works fine with empty array", () => {
-    assert.strictEqual(mostLikes(emptyArray), null);
-  });
-
-  test("fails with gibberish input", () => {
-    const failedCall = () => {
-      mostLikes(gibberish);
-    };
-    assert.throws(failedCall, Error);
-  });
-});
diff --git a/parts/4/blogApp/tests/mostPosts.test.js b/parts/4/blogApp/tests/mostPosts.test.js
deleted file mode 100644
index 1b32452..0000000
--- a/parts/4/blogApp/tests/mostPosts.test.js
+++ /dev/null
@@ -1,54 +0,0 @@
-const { test, describe } = require("node:test");
-const assert = require("node:assert");
-const { mostPosts } = require("../src/utils");
-
-describe("most posts ", () => {
-  const posts = [
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 5,
-      __v: 0,
-    },
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 2,
-      __v: 0,
-    },
-    {
-      _id: "123",
-      title: "Lololo",
-      author: "John Doe",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 1,
-      __v: 0,
-    },
-  ];
-
-  const emptyArray = [];
-
-  const gibberish = "asdaSd123asd";
-
-  test("finds top author  properly", () => {
-    assert.deepStrictEqual(mostPosts(posts), {
-      author: "Edsger W. Dijkstra",
-      posts: 2,
-    });
-  });
-
-  test("works fine with empty array", () => {
-    assert.strictEqual(mostPosts(emptyArray), null);
-  });
-
-  test("fails with gibberish input", () => {
-    const failedCall = () => {
-      mostPosts(gibberish);
-    };
-    assert.throws(failedCall, Error);
-  });
-});
diff --git a/parts/4/blogApp/tests/reverse.test.js b/parts/4/blogApp/tests/reverse.test.js
deleted file mode 100644
index 59f044d..0000000
--- a/parts/4/blogApp/tests/reverse.test.js
+++ /dev/null
@@ -1,22 +0,0 @@
-const { test } = require('node:test')
-const assert = require('node:assert')
-
-const reverse = require('../src/utils.js').reverse
-
-test('reverse of a', () => {
-  const result = reverse('a')
-
-  assert.strictEqual(result, 'a')
-})
-
-test('reverse of react', () => {
-  const result = reverse('react')
-
-  assert.strictEqual(result, 'tcaer')
-})
-
-test('reverse of saippuakauppias', () => {
-  const result = reverse('saippuakauppias')
-
-  assert.strictEqual(result, 'saippuakauppias')
-})
\ No newline at end of file
diff --git a/parts/4/blogApp/tests/totalLikes.test.js b/parts/4/blogApp/tests/totalLikes.test.js
deleted file mode 100644
index 1bf1071..0000000
--- a/parts/4/blogApp/tests/totalLikes.test.js
+++ /dev/null
@@ -1,43 +0,0 @@
-const { test, describe } = require("node:test");
-const assert = require("node:assert");
-const { totalLikes } = require("../src/utils");
-
-describe("total likes ", () => {
-  const posts = [
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 5,
-      __v: 0,
-    },
-    {
-      _id: "5a422aa71b54a676234d17f8",
-      title: "Go To Statement Considered Harmful",
-      author: "Edsger W. Dijkstra",
-      url: "https://homepages.cwi.nl/~storm/teaching/reader/Dijkstra68.pdf",
-      likes: 2,
-      __v: 0,
-    },
-  ];
-
-  const emptyArray = [];
-
-  const gibberish = "asdaSd123asd";
-
-  test("counts likes properly", () => {
-    assert.strictEqual(totalLikes(posts), 7);
-  });
-
-  test("works fine with empty array", () => {
-    assert.strictEqual(totalLikes(emptyArray), 0);
-  });
-
-  test("fails with gibberish input", () => {
-    const failedCall = () => {
-      totalLikes(gibberish);
-    };
-    assert.throws(failedCall, Error);
-  });
-});
diff --git a/parts/4/notes.md b/parts/4/notes.md
deleted file mode 100644
index e4593b6..0000000
--- a/parts/4/notes.md
+++ /dev/null
@@ -1,8 +0,0 @@
-Exercises:
-* [X] 4.1
-* [X] 4.2
-* [X] 4.3
-* [X] 4.4
-* [X] 4.5
-* [X] 4.6
-* [X] 4.7