A linked-device WhatsApp API. Not the official Meta platform.

The four steps

• Create an account. The trial is 4 days and does not need a card.
• Create an instance and link the phone: WhatsApp → Linked devices → Link a device. Scan the QR code, or request a pairing code and type it on the phone.
• Copy the instance API key. The key selects the number. Do not send instance_id in the message body.
• From your server, POST https://api.flaresend.com/send-message with recipients, type, and text. Point a webhook at your HTTPS URL to receive replies.

What we store

API traffic uses HTTPS. We keep usage metrics for the dashboard: message counts, delivery status, and timestamps. We do not keep the content of your messages for product analytics. The WhatsApp session credentials that keep the link alive are stored encrypted. If the session drops because of a network blip, we reconnect with that saved session. If the number is logged out on the phone, you link it again.

Opt-in rules

Only message people who expect it. That means a code they just requested, a receipt for a payment they made, or an order update they agreed to at checkout. Ask in plain language, store the answer, and honour STOP.

• Do not upload a bought list or a group of people who never heard of you.
• Do not send the same marketing text to thousands of cold numbers. That path gets numbers restricted, and it is a poor fit for this product. Above roughly 10,000 messages a day to cold lists, use Meta's official platform.
• On a new number, start with about 20–30 messages a day and increase over a couple of weeks. That guidance is also on our features page.
• Keep a SIM that is dedicated to the business when you can, so a restriction does not take the founder's personal chat with it.

There is no green tick on this path, and WhatsApp's own rules still apply. The comparison with Meta's Cloud API is the place to decide which one you actually need.

Questions

How does the QR code or pairing code link work?

On the phone, open WhatsApp, then Linked devices, then Link a device. Scan the QR code FlareSend shows, or enter the pairing code. That creates a linked session for that number, the same mechanism WhatsApp Web uses. Your server then sends through that session with the instance API key.

What should we tell customers when we ask them to opt in?

Say what you will send, on which number, and how they can stop. A checkout checkbox such as "Send my receipt and delivery updates on WhatsApp" is enough for transactional messages. Store the answer. Do not add them to promotions unless they agreed to that separately.

When should we use Meta's official platform instead?

Use the official WhatsApp Business Platform when you need a verified business name, approved templates, or more than about 10,000 messages a day, especially to large marketing lists. FlareSend is the faster path for opt-in transactional messages from a small team. See the comparison page for the full trade-off.

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