The big picture: Back in 2014, Facebook made one of the largest acquisitions in tech history when it bought WhatsApp for $16 billion. Four years later, the social media giant is starting to monetizing the incredibly popular service with a set of new tools that help connect businesses with their customers over the platform.

Following a limited test run, WhatsApp for Business arrived on Android back in January. Now, Facebook is launching its Business API, providing companies with new means to stay in contact with people.

The rule that businesses can only message WhatsApp users who contact them first or share their phone number remains, but companies can now programmatically send information such as shipping confirmations, appointment reminders, receipts, or event tickets. They’ll also be able to offer real-time customer support and accept inquiries using click-to-chat buttons on their websites or Facebook pages.

Messages from businesses use the same end-to-end encryption as other WhatsApp communications. To make money from the service, companies that are slow to respond to customers are charged a fee. Answering someone within 24 hours costs nothing, but replying any later will incur a charge.

The Business app that launched in January brought features such as company profiles, messaging analytics, and Twitter-style ‘Verified account’ badges. While WhatsApp said the app would initially be free, it noted that paid-for capabilities would be added at some point in the future. It's possible the app will eventually allow businesses to receive payments from customers, something else WhatsApp could charge companies for.

Right now, the Business API is available to just 90 firms, including Uber, Booking.com, and KLM Airlines, with more being added in the future.

You can download the latest version of WhatsApp for Android here.