diff --git a/parts/3/notes.md b/parts/3/notes.md
index a765a7f..44bb16f 100644
--- a/parts/3/notes.md
+++ b/parts/3/notes.md
@@ -2,6 +2,6 @@ Exercises:
 * [X] 3.1
 * [X] 3.2
 * [X] 3.3
-* [ ] 3.4
-* [ ] 3.5
+* [X] 3.4
+* [X] 3.5
 * [ ] 3.6
diff --git a/parts/3/phonebookBackend/index.js b/parts/3/phonebookBackend/index.js
index de8237d..4abbd75 100644
--- a/parts/3/phonebookBackend/index.js
+++ b/parts/3/phonebookBackend/index.js
@@ -48,6 +48,38 @@ app.get("/api/persons/:id", (request, response) => {
   }
 });
 
+app.post("/api/persons/", (request, response) => {
+  if (!request.body.name || !request.body.number) {
+    return response.status(400).json({
+      success: false,
+      message: "Malformed body.",
+    });
+  }
+
+  const nameIsInPhonebook = persons.find(
+    (person) => person.name == request.body.name
+  );
+
+  if (nameIsInPhonebook) {
+    return response.status(409).json({
+      success: false,
+      message: "Name already in phonebook.",
+    });
+  }
+
+  const newId = Math.floor(Math.random() * 100_000_000 * 21);
+
+  const personData = {
+    id: newId,
+    name: request.body.name,
+    number: request.body.number,
+  };
+
+  persons.push(personData);
+
+  return response.status(201).json(personData);
+});
+
 app.delete("/api/persons/:id", (request, response) => {
   const idToDelete = request.params.id;
 
diff --git a/parts/3/phonebookBackend/requests/create_person.rest b/parts/3/phonebookBackend/requests/create_person.rest
new file mode 100644
index 0000000..45a0a2f
--- /dev/null
+++ b/parts/3/phonebookBackend/requests/create_person.rest
@@ -0,0 +1,7 @@
+POST  http://localhost:3001/api/persons/
+Content-Type: application/json
+
+{
+    "name": "MMMonica",
+    "number": "123-456"
+}
\ No newline at end of file