Free QR code API — scannable QR codes from a URL, PNG or SVG, no key

You need a QR code in an app, an email, a ticket PDF, a poster, a terminal script — and you don't want to vendor a QR library into every codebase, run an image service, or paste strings into a generator website one at a time. The URL-parameter pattern solves this: put your data in a query string, get image bytes back, and let an <img> tag or a curl -o do the rest.

Mockbird serves QR codes exactly that way — no key, no signup, no watermark, and the same URL returns the same bytes forever, so caches and CDNs love it:

The 10-second version

# a scannable 256x256 PNG — this URL works right now
curl -o qr.png "https://mockbird.mockbird.workers.dev/m/demo/qr?data=https%3A%2F%2Fexample.com"

# bigger, with a size in the path
curl -o qr.png "https://mockbird.mockbird.workers.dev/m/demo/qr/500?data=hello+world"

# vector output for print (crisp at any scale)
curl -o qr.svg "https://mockbird.mockbird.workers.dev/m/demo/qr.svg?data=hello+world"

Or straight in HTML — the classic use:

<img src="https://mockbird.mockbird.workers.dev/m/demo/qr?data=https%3A%2F%2Fexample.com"
     width="256" height="256" alt="QR code">

All the parameters

Payloads people actually encode

# a URL (the 95% case)
…/qr?data=https%3A%2F%2Fexample.com%2Fmenu

# wifi credentials (scan → join network)
…/qr?data=WIFI%3AT%3AWPA%3BS%3Amynet%3BP%3Asecret123%3B%3B

# mailto / tel
…/qr?data=mailto%3Ahello%40example.com
…/qr?data=tel%3A%2B15551234567

# plain text (event check-in codes, ticket ids)
…/qr?data=TICKET-2026-000451

Encoding tip: always URL-encode the payload. &, ?, #, + and spaces inside an unencoded data= will be eaten by query parsing — encodeURIComponent() in JS, urllib.parse.quote() in Python, --data-urlencode with curl.

Generate a batch from your shell

> for id in 001 002 003; do
    curl -s -o "ticket-$id.png" \
      "https://mockbird.mockbird.workers.dev/m/demo/qr/400?data=TICKET-$id&ecc=Q"
  done

Because output is deterministic, re-running the loop produces byte-identical files — safe for build pipelines and reproducible artifacts.

Honest comparison

Being upfront: goqr.me has run a solid free QR endpoint for over a decade and also reads QR codes — if you need decoding or EPS output, use it. QuickChart is open-source (you can self-host the AGPL server) and supports embedding a center logo image, which we don't. Mockbird's angle: the QR endpoint lives next to your mock REST API, placeholder images, avatars and OG cards under one project URL — one host to remember for everything a frontend needs before the real backend exists. And offline/air-gapped builds should always vendor a library instead of calling anyone's API.

Pairs well with the rest of your mock backend

Seeded mock data + QR endpoint composes nicely: render a QR per record with nothing but string interpolation.

// e.g. a ticket list from the demo API, each with its own QR
const res = await fetch("https://mockbird.mockbird.workers.dev/m/demo/orders?limit=5");
const orders = await res.json();
document.body.innerHTML = orders.map(o =>
  `<img src="https://mockbird.mockbird.workers.dev/m/demo/qr/160?data=ORDER-${o.id}" width="160">`
).join("");

Limits

• data capped at 1000 characters. QR byte-mode capacity is 2,953 bytes at ecc=L and 1,273 at ecc=H — 1000 ASCII chars fit at every level; heavy multi-byte UTF-8 can overflow at high ECC (the error says so — drop to ?ecc=L or shorten).
• PNG capped at 1,000,000 pixels (1000×1000); use ?format=svg for larger.
• Dense codes need room: if size is smaller than one pixel per module, you get a 400 telling you the minimum.
• Counts toward the project's daily request cap (the shared demo project has a generous one; your own project gets its own).

Full reference in the docs. More image guides: placeholder image API · PNG placeholder API · OG image API · chart image API · avatar API · identicon API. Create your API →