tappSmart address book addappt released an update this morning with a new feature called “tapp” — letting users quickly send short messages and emoji that appear as custom notifications across iPhone and Android, leveraging a feature of smartphones more commonly used for alerts from the apps themselves.

It’s the latest take on “one-bit communication,” giving users a quick way to send messages to individual friends and groups of people who are using the app.

The main selling point is the simplicity. No history of the notifications is stored (on the device or the addappt servers), and there’s no bcc/or cc list for group messages, which also means there’s no ‘reply all.’

“The notification is the message,” explained addappt CEO and co-founder Mrinal Desai, a startup veteran who was LinkedIn’s first business development manager.

Here’s how it works.

Desai says he envisions this replacing the codes that people have come up with to alert one another, such as two missed calls signaling when someone is running late. It also helps satisfy the desire — illustrated famously by the app “Yo” — for ways to touch base quickly, just to let someone know you’re thinking about them.

Desai expects the primary use case for the group “tapp” to be one-way notifications, such as a church organizer or a grade school teacher sending out a quick notification to a group. There’s no limit on the size of the group, although group tapps can only be sent from iOS for now. (Group tapps can be received across iOS and Android.)

That’s the biggest new feature in addappt 2.0, a redesigned version of the app released today for iPhone and Android.

The app’s flagship feature is the ability for friends to update their information in your address book. Addappt syncs with the smartphone’s native address book, and allows addappt users to connect with one another — automatically updating contact information when it’s changed by the contact, and replicating that information across cloud services and apps connected to the user’s phone.

Addappt’s development team is in the Seattle region, including the company’s CTO and co-founder, software design engineer Jorge Ferreira, a University of Washington alum and 12-year veteran of Microsoft. Another former Microsoftie, Carlos Brito, is the company’s principal developer.

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