With Knopfpost, your child gets their own mailbox on a device you set up completely: only mail from people you approve, nothing else. Grandma, Grandpa and friends just use WhatsApp, which they already have, no new account needed.
For Android · family sends with
WhatsApp · for children aged around 2 to 6I found it a shame that everything someone wanted to send my child landed with me first. And I wanted my child to see what Grandma, Grandpa and friends are up to too, not just always the other way around.
Steffi, built Knopfpost
Parents send countless pictures of their children to grandparents, aunts, uncles and friends. It rarely goes the other way: Grandma's hike, Grandpa's new garden, an aunt's holiday, that rarely lands with the child directly. Knopfpost turns that around.
A video from the summit, with her own voice over it. Not just a photo in the family group chat that gets lost.
One tap on the envelope, and there he is: Grandpa's new puppy. No adult has to show the child, they find their mail all on their own.
Even when she lives far away, a short voice note makes the closeness felt.
Knopfpost turns an old device into a personal family mailbox — and the family sends from WhatsApp, the app they already have. No new app for anyone.
On a tablet or phone. You approve who is allowed to send — and they need no Knopfpost account, just WhatsApp.
Approved family send photos, voice notes or short videos — straight from WhatsApp, the app they already use every day.
An envelope shows that something new has arrived. One tap starts the message.
And then? Right back to playing.
Screen time parents actually feel good about. Knopfpost is deliberately not a messenger or a games device. There is just one thing to discover: mail from trusted people.
You decide as parents who is allowed to send anything at all. Nobody else gets through.
Your child doesn't get a device for free use, but one you lock to Knopfpost. A single tap isn't enough to leave it, that's enforced technically, not just a setting.
There is nothing to buy in the child's view, and nothing competing for their attention. That's true today in the beta, and it stays true once Knopfpost is a finished product.
Once a message has been viewed, we delete it from our own servers within a week. On the tablet itself it stays, saved to the device's own photo gallery, so your family can keep it for as long as you want.
Knopfpost does not need a new device. An unused Android tablet or phone can become a personal mailbox.
Android 6.0 is the minimum version for installation. Suitability of older and lower-powered devices is still being tested.
The essentials for families who would like to try Knopfpost.
A personal mailbox for photos, voice notes and short videos from trusted people.
For children aged around 2 to 6.
An old Android phone or tablet, Wi-Fi, and family who can send a WhatsApp. No Knopfpost account is needed for the people sending.
No. Senders just use WhatsApp, which they already have on their phone. No download, no sign-up, no new account. Learn more about WhatsApp.
Only people parents approve in the app.
The device is set up for Knopfpost so children stay with their mail and cannot get into other areas.
Yes. Approved family members send photos, voice notes and short videos straight from WhatsApp — the app they already have. No extra account to create.
Yes. Family and friends can send over Telegram instead – just use whichever messenger you already have.
Family and friends already send from 
Knopfpost is being built with the first families right now. Family and friends can already send from WhatsApp — you can join as a test family today.
Two short steps, then you can set up Knopfpost on a dedicated tablet or phone.
Unlocks your access (needs a Google account).
Confirms you as a beta tester in the Play Store.