Free Wi-Fi QR code API — scan-to-join codes from a URL, no key

Point a phone camera at the right QR code and it offers to join the Wi-Fi network — no typing a 20-character passphrase off the router sticker. Café table tents, guest-room welcome cards, Airbnb host sheets, office visitor desks, event posters: same trick everywhere. Generator websites make these one at a time; if you're rendering them from an app, a template, or a script for fifty meeting rooms, you want an API.

Mockbird's QR endpoint has dedicated Wi-Fi parameters — you pass the network name and password, the server builds the payload:

The 10-second version

<img src="https://mockbird.mockbird.workers.dev/m/demo/qr?ssid=GuestCafe&password=latte-art" width="256">

# or download it
curl -o wifi.png "https://mockbird.mockbird.workers.dev/m/demo/qr/400?ssid=GuestCafe&password=latte-art"

Scan that with any modern phone camera and it prompts to join GuestCafe. No key, no signup, no watermark — and the same URL returns the same bytes forever, so it's safe to cache, print, and re-render in build pipelines.

Why a dedicated Wi-Fi mode (the escaping problem)

Wi-Fi QR codes encode a plain-text payload that phone cameras recognize:

WIFI:T:WPA;S:GuestCafe;P:latte-art;;

Simple — until the network name or password contains ; , : " or \. Those are structural characters in the payload and must be backslash-escaped, and then the whole string must be URL-encoded to survive a query string. Two layers of escaping is exactly the kind of thing that works in the demo and breaks on the one router whose passphrase contains a semicolon. With ?ssid= + ?password= you do neither — standard URL encoding of your values is all that's left, and the server handles the payload layer:

# password is `latte;art` — no payload escaping on your side, just normal URL encoding
…/qr?ssid=Guest%20Cafe&password=latte%3Bart

# raw ?data= still works if you'd rather build the payload yourself
…/qr?data=WIFI%3AT%3AWPA%3BS%3AGuest%20Cafe%3BP%3Alatte%5C%3Bart%3B%3B

Those two URLs return byte-identical images — the Wi-Fi params are sugar over the same encoder, not a different code path.

All the parameters

Recipes

# open network (no password prompt, phone just joins)
…/qr?ssid=Library%20Guest&security=nopass

# hidden network
…/qr?ssid=BackOffice&password=s3cret-pass&hidden=1

# print-quality poster: bigger, high error correction (survives coffee stains + staples)
…/qr/800?ssid=GuestCafe&password=latte-art&ecc=H

# crisp vector for a PDF welcome card
…/qr.svg?ssid=GuestCafe&password=latte-art

A printable welcome card is a dozen lines of HTML:

<div style="text-align:center;font-family:sans-serif;border:1px solid #ccc;
            border-radius:12px;padding:24px;width:280px">
  <h2>Welcome! Get online</h2>
  <img src="https://mockbird.mockbird.workers.dev/m/demo/qr/220?ssid=GuestCafe&password=latte-art"
       width="220" height="220" alt="Scan to join our Wi-Fi">
  <p>Network: <b>GuestCafe</b><br>Password: <b>latte-art</b></p>
</div>

And a batch — one code per meeting room — is a shell loop:

> for room in alpha beta gamma; do
    curl -s -o "wifi-$room.png" \
      "https://mockbird.mockbird.workers.dev/m/demo/qr/400?ssid=Office-$room&password=changeme-$room&ecc=Q"
  done

The password is in the URL — think before you paste

A Wi-Fi QR code's entire purpose is to hand out the passphrase, so anyone who can scan the printed code has the credentials — that part is by design. But the URL contains the password too: it will sit in your browser history, your shell history, and any proxy logs between you and us. Mockbird redacts password= from its own request inspector (on every project — the shared demo project's inspector is public, so this matters), and image responses carry no copy of the payload beyond the code itself. For a real office network, generate the image once with curl -o, keep the file, and don't embed the live URL in anything public. For guest networks whose password is on a chalkboard anyway, embed away.

Honest comparison

Being upfront: QuickChart documents the WIFI: format well, has an interactive Wi-Fi builder on their site, and supports logo embedding and fancy dot styles we don't — if you want a branded code, use it. goqr.me has run a reliable free QR endpoint for over a decade and can also decode codes. wificard.io is a lovely open-source page for printing a one-off fridge card — if you need exactly one code and no automation, it's the fastest path. Mockbird's angle is the API case: credentials in, image out, escaping handled, deterministic output, and the endpoint lives next to a full mock REST API, placeholder images, avatars, OG cards and charts under one project URL.

Limits

• ssid ≤32 chars, password ≤63 chars (the real-world 802.11/WPA limits — longer values wouldn't work on the router either).
• Wi-Fi payloads are short, so they encode comfortably at every error-correction level — use ?ecc=H for anything that gets printed.
• PNG capped at 1,000,000 pixels (1000×1000); ?format=svg beyond that.
• 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: QR code API · placeholder image API · OG image API · chart image API · avatar API · identicon API. Create your API →