index.js

const http = require('http');

const server = http.createServer((req, res) => {
  if (req.method === 'POST' && req.url === '/') {
    let body = '';

    req.on('data', chunk => {
      body += chunk.toString();
    });

    req.on('end', () => {
      const responseHeaders = {};
      for (const [key, value] of Object.entries(req.headers)) {
        responseHeaders[key] = value;
      }

      res.writeHead(200, responseHeaders);
      res.end(body);
    });
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('Not Found');
  }
});

const PORT = 8000;
server.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});