It’s stable, it’s simple, and it respects the browser's security model. For anyone building point-of-sale, ticketing, or logistics software, it’s the silent workhorse that just works.

That's it. No WebUSB permission popups. No serial-port API browser compatibility hell. Just a POST request. It requires a local install. The user (or your MDM) must install the Epson Easy Print Module application once per machine. That's fine for fixed kiosks or POS terminals, but impossible for a "visit this website and print from your phone" use case.

// Step 1: Encode your ESC/POS commands const commands = [ 0x1B, 0x40, // Initialize printer 0x1B, 0x61, 0x01, // Center align ...textToBytes("THANK YOU\n"), 0x1D, 0x56, 0x42, 0x00 // Cut paper ]; const base64Data = btoa(String.fromCharCode(...commands));

// Step 2: Send to local module const response = await fetch('http://localhost:8008/print', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ device: 'TM-T20X', data: base64Data }) });

But the API itself is refreshingly simple.