Silent receipt and label printing from any web app

Your web app sends JSON. A small agent on the shop computer prints it. No print dialog, no Java, no yearly fee.

Buy Thermalink, from $49 Read the quick start

const tl = new Thermalink();

await tl.print(
  Thermalink.receipt()
    .title('BLUE DOOR CAFE')
    .row('Flat white x2', '8.00')
    .row('TOTAL', '8.00', { bold: true })
    .qr('https://example.com/r/A1B2C3')
    .cut()
);

Thermalink: a receipt rendered by the agent next to the JavaScript that produced it

The problem it solves

If you build a POS, restaurant, retail or warehouse web app, you have met this wall. window.print() shows a dialog and cannot cut paper or open the cash drawer. WebUSB only works in Chromium browsers and, on Windows, is refused by the printer's own driver. QZ Tray works, but it bundles Java and its certificate tier is a yearly fee.

Thermalink is one small program that runs next to the printer, plus an 8 KB JavaScript SDK.

What it does

Same receipt on every brand

Image mode draws the receipt as a bitmap at your printer's real width, so it does not depend on built-in fonts, column counts or code pages.

Calibrate in two minutes

thermalink calibrate prints width bars and a ruler. Save the width per printer and the layout fills the paper.

Receipt layout in JSON

Rows, wrapping columns, dividers, QR codes, barcodes, logos, paper cut and cash drawer kick.

USB, network and labels

USB printers through the OS print queue, network printers on port 9100, and raw ZPL, TSPL or EPL for label printers.

Locked to your site

Listens on localhost only. An origin allowlist decides which websites may print, with an API key for scripts.

Source included

The full Go source and tests ship with it, so you can audit it or build it yourself.

How it compares

	Thermalink	QZ Tray	window.print()	WebUSB / Web Serial
Silent, no dialog	Yes	Yes (warning prompts unless you buy a certificate)	No	Yes
Price	One-time	$599/year for premium/certificate (buy.qz.io, October 2026)	Free	Free
Runtime to install	None, a single ~7 MB file	Bundled Java	None	None
Browsers	All modern	All	All	Chromium only
USB printer still usable by Windows	Yes	Yes	Yes	No (driver conflict)
Network printers (9100)	Yes	Yes	Through the OS	No
Cut, drawer, QR, barcodes, logos	Yes	Yes, you build the bytes	No, or unreliable	You build the bytes
JSON receipt layout	Built in	No	CSS	No

Tested, honestly

The ESC/POS and raster output, layout, QR, barcode and image encoding, printer profiles and security checks are covered by automated tests. On real hardware it has been tested end to end (Chrome, agent, printer) on one printer: a BIXOLON SRP-352plusIII on Windows 11.

Other ESC/POS printers use the same standard commands and are expected to work, but have not been individually tested. The macOS and Linux binaries are built and use CUPS, but have not been hardware-tested. The compatibility page lists exactly what has been verified.

Not for you if you only print A4 or Letter documents (the browser's print dialog is fine for that), or the printer is on a different network from the computer running the agent.

Price

Standard

$49

One application. Install the agent on unlimited computers of that app's users.

Unlimited / Agency

$149

All your apps and client projects, and you may rebrand the agent inside your own installers.

One-time payment, including all 1.x updates. Binaries are not code-signed, so Windows SmartScreen and macOS Gatekeeper will ask once.

Buy on Gumroad See the JSON reference

Free things

ESC/POS, ZPL and TSPL cheat sheet: the commands with their bytes, on one page.
receipt-fit: a tiny script that makes window.print() use the receipt's real height.
Only need window.print()? The Receipt Print Kit ($9) has the stylesheet and eight templates.