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A WhatsApp QR code that opens a chat, pre-typed
For a lot of businesses WhatsApp is the phone number. A code on the window turns a passer-by into a conversation without them typing anything.
Get the number format right, or nothing works
The number must be in full international format: country code, then the number, with no plus sign, no spaces, no dashes, no leading zero.
A Qatari number written locally as 5551 2345 becomes 97455512345. A UK number written 07700 900123 becomes 447700900123 — note the leading zero disappears when the country code goes on.
The leading zero is the usual mistake, and the result is a link WhatsApp cannot match to an account, or matches to the wrong one. The generator removes spaces, dashes, a leading + and a leading 00 for you. It cannot know to drop a local leading zero, so type the number with the country code in front and without that zero.
Pre-type the first message
A WhatsApp link can carry a message that appears already typed in the box, waiting to be sent. This is more useful than it sounds: it removes the moment where someone has opened a chat and does not know what to say.
Keep it short and specific to where the code is. "Hi, I would like to book a table" on a restaurant window. "Hi, I am asking about the blue chair in the window. Is it still available, and can you deliver?" outside a furniture shop. The customer can edit it, and often will, but they are now in a conversation rather than staring at an empty box.
What a pre-typed message costs
The message travels inside the link, so it changes the code. Measured with this site's encoder at level H, for one Qatari number:
| Pre-typed message | Link characters | Modules across | Module at 3 cm |
|---|---|---|---|
| No message | 25 | 33 | 0.73 mm |
| Hi, I would like to book a table | 79 | 49 | 0.53 mm |
| Hi, I am asking about the blue chair… (the 95-character furniture-shop message above) | 168 | 69 | 0.39 mm |
| مرحبا، أود حجز طاولة | 142 | 65 | 0.41 mm |
Spaces become %20 and commas %2C, and every letter outside basic Latin is written as its UTF-8 bytes, three characters per byte. An Arabic letter is two bytes, so the 20-character Arabic message makes a 142-character link, longer than the 79 of the 32-character English one. Keep the pre-typed text short, and print the code larger when it is in Arabic, Cyrillic or another non-Latin script. QR codes in other languages measures the same effect on plain text.
Business account or personal
The code works with either. A WhatsApp Business account adds things worth having if this becomes a real channel: an away message for when you are closed, a greeting for first contact, and labels to keep enquiries organised.
If you expect more than a handful of messages a day, set up the away message before you print anything. A code that produces silence outside business hours is worse than no code.
Where to put it
On the window, at eye level, is the classic. It catches people who walked past while you were closed, which is traffic you otherwise lose entirely.
On the receipt or the invoice it becomes a support channel. On a product label it becomes a question channel — "message us about this item" invites the question at the moment someone has it.
Test with a phone that is not yours
Scanning it on the business phone itself proves little: a number pointing at your own account opens a chat with yourself. Borrow a phone that has never messaged you, scan the printed code, and check the chat opens to the right number with the right text.
Then answer it. A code that opens a chat nobody replies to costs more goodwill than it earns.
Opens a chat through WhatsApp’s own wa.me link, first message already typed.
Make a WhatsApp QR code →