Developer

Send WhatsApp messages from a link

4 min readUpdated October 2026Pro · Custom

Some software can only open a web address, for example a billing or accounting tool that sends SMS through a gateway link. With a send-by-URL key, that software can send WhatsApp messages the same way: opening the link sends the message. The key can only send, and it is separate from your main API key.

Before you begin

You need: (1) a plan with API access (Pro or Custom), (2) to be a workspace admin, (3) an approved WhatsApp template for customers who have not messaged you in the last 24 hours, and (4) money in your wallet.

Get your send-by-URL key

Open Settings → Developer

Stay on the API Keys tab. Find the card Send messages from a link.

Click Generate send-by-URL key

Confirm in the box by clicking Generate. Your main API key is not affected.

Copy the key and the link

The page shows your full key once, with Copy key, and an example link with your key already filled in, with Copy link. Paste the link into your software, then replace the numbers, template name and values with your own. Click Done when you have saved it.

Tanvik never shows the full key again. After you click Done, the page shows only a short preview. If you lose the key, rotate it to get a new one.

Keys that start with tvku_ are send-by-URL keys. Your main API key starts with tvk_ and does not work in a link.

What goes in the link

Your link has the form below. The page shows the full address in front of it, so always copy it from there.

…?api_key=YOUR_URL_KEY&to=9876543210,9123456789&template=your_template_name&lang=en&vars=Rahul|5,000|10-Oct

Part	What to put
api_key	Your send-by-URL key.
to	Phone numbers, separated by commas. 10-digit Indian mobile numbers work as they are. For other countries, add the country code. Up to 100 numbers per link.
template	The name of an approved WhatsApp template. Needed for any customer who has not messaged you in the last 24 hours.
lang	The template's language code, such as en or hi. If you leave it out, it is en.
vars	The values for the template's {{1}}, {{2}} and so on, in order, separated by \|. The bar keeps amounts like 5,000 in one piece.
image_url or document_url	Optional header image or PDF, for templates that have one.
text	Free text instead of a template. It is only delivered to customers who messaged you in the last 24 hours.

Use either template or text in one link, not both. Some gateways call the number and message parts mobileNos and message. Those names work too.

Test with your own number first. Put your number in to, open the link in a browser, and check the message arrives before you connect your software.

What the link returns

Opening the link shows a short reply. It tells you whether Tanvik took the message, not whether the customer has read it. For delivery, check why a message failed and your inbox.

Reply	Meaning
accepted	One number: Tanvik took the message.
queued	Several numbers: all were taken.
partial_failure	Several numbers: some were taken and some were not. The reply lists each number with its result.
An error	The message was not sent. The reply says why, for example the key is missing, wrong or revoked, to is empty, both template and text were given, or there are too many numbers.

How these messages are billed

Messages sent from a link are paid from your wallet at your message rates. They do not use your 1,000 free messages, because those are for the inbox and the AI Agent. If your balance is too low, the message is not sent. See Free messages and how messages are billed.

Rotate or revoke the key

Once you have a key, the card shows a short preview and either Last used with the time, or Not used yet. It also keeps the link format and the table of parts for you to copy.

Button	What it does
Rotate	Makes a new key. The current key stops working immediately, so update the link in your software right away.
Revoke	Switches the key off. Every link using it stops working immediately. Your main API key is not affected.

Anyone who sees the link can send messages from your number. The key is inside the link, so it can end up in logs or browser history. Paste it only into software you trust, and revoke it if you think it was exposed.

Common questions

I do not see the Send messages from a link card.

Only workspace admins see it, and only on a plan with API access. Teammates see Admins only. A plan without API access sees API access isn't enabled on your plan. See Plans, invoices and GST.

The link worked but the customer got nothing.

Outside the 24-hour window only a template is delivered. Use template instead of text, with a template that is approved and written in the same language as lang.

The link stopped working.

Someone may have rotated or revoked the key. Generate a new one and update the link in your software.

Can I use my main API key in a link?

No. A link needs a send-by-URL key. Your main API key stays in request headers. See Use the Tanvik API and connect Claude.

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