npm install pdf-lib

import { PDFDocument, rgb, StandardFonts } from 'pdf-lib';

const pdfDoc = await PDFDocument.create();
const page = pdfDoc.addPage([595, 842]); // A4
const font = await pdfDoc.embedFont(StandardFonts.Helvetica);

page.drawText('Invoice #1234', {
  x: 50, y: 780,
  size: 24,
  font,
  color: rgb(0, 0, 0),
});

page.drawLine({ start: { x: 50, y: 760 }, end: { x: 545, y: 760 }, thickness: 1 });

const pdfBytes = await pdfDoc.save();
// In Node.js:
await fs.writeFile('invoice.pdf', pdfBytes);
// In browser:
const blob = new Blob([pdfBytes], { type: 'application/pdf' });