diff --git a/src/createServer.js b/src/createServer.js
index 1cf1dda..6f18625 100644
--- a/src/createServer.js
+++ b/src/createServer.js
@@ -1,8 +1,137 @@
 'use strict';
 
+const http = require('http');
+const fs = require('fs');
+const path = require('path');
+const querystring = require('querystring');
+
 function createServer() {
-  /* Write your code here */
-  // Return instance of http.Server class
+  return http.createServer((req, res) => {
+    if (req.method === 'GET' && req.url === '/') {
+      res.writeHead(200, {
+        'Content-Type': 'text/html',
+      });
+
+      res.end(`
+        <!doctype html>
+        <html lang="en">
+          <head>
+            <meta charset="UTF-8" />
+            <title>Add expense</title>
+          </head>
+          <body>
+            <h1>Add expense</h1>
+
+            <form method="POST" action="/add-expense">
+              <label>
+                Date
+                <input type="date" name="date" />
+              </label>
+              <br />
+              <label>
+                Title
+                <input type="text" name="title" />
+              </label>
+              <br />
+              <label>
+                Amount
+                <input type="text" name="amount" />
+              </label>
+              <br />
+              <button type="submit">Submit</button>
+            </form>
+          </body>
+        </html>
+      `);
+
+      return;
+    }
+
+    if (req.method === 'POST' && req.url === '/add-expense') {
+      let body = '';
+
+      req.on('data', (chunk) => {
+        body += chunk.toString();
+      });
+
+      req.on('end', () => {
+        const contentType = req.headers['content-type'] || '';
+        let expense = {};
+
+        try {
+          if (contentType.includes('application/json')) {
+            expense = JSON.parse(body);
+          } else {
+            expense = querystring.parse(body);
+          }
+        } catch (error) {
+          res.writeHead(400, {
+            'Content-Type': 'text/plain',
+          });
+          res.end('Invalid request body');
+
+          return;
+        }
+
+        const { date, title, amount } = expense;
+
+        if (!date || !title || !amount) {
+          res.writeHead(400, {
+            'Content-Type': 'text/plain',
+          });
+          res.end('Missing required fields');
+
+          return;
+        }
+
+        const dataPath = path.resolve(__dirname, '../db/expense.json');
+
+        fs.writeFileSync(dataPath, JSON.stringify({ date, title, amount }));
+
+        if (contentType.includes('application/json')) {
+          res.writeHead(200, {
+            'Content-Type': 'application/json',
+          });
+          res.end(JSON.stringify({ date, title, amount }));
+
+          return;
+        }
+
+        res.writeHead(200, {
+          'Content-Type': 'text/html',
+        });
+
+        res.end(`
+          <!doctype html>
+          <html lang="en">
+            <head>
+              <meta charset="UTF-8" />
+              <title>Expense saved</title>
+            </head>
+            <body>
+              <h1>Expense saved</h1>
+              <pre>${escapeHtml(JSON.stringify({ date, title, amount }, null, 2))}</pre>
+              <a href="/">Back</a>
+            </body>
+          </html>
+        `);
+      });
+
+      return;
+    }
+
+    res.writeHead(404, {
+      'Content-Type': 'text/plain',
+    });
+    res.end('Page not found');
+  });
+}
+
+function escapeHtml(text) {
+  return text
+    .replaceAll('&', '&amp;')
+    .replaceAll('<', '&lt;')
+    .replaceAll('>', '&gt;');
 }
 
 module.exports = {
