Kinzo

BackendSide

About this app

Kinzo is a messenger that works without the internet. Two devices on the same
Wi-Fi find each other and talk directly - no account, no server in the middle,
nothing uploaded anywhere.

Messages travel encrypted, straight from one device to the other. Because there
is no server, there is nothing in between to hold a copy.

WHERE IT HELPS

- At home when the internet is down but the router is still up
- Workshops, warehouses, basements and boats with no signal
- Classrooms and offices, passing files around without the cloud
- Anywhere your connection is slow, metered, or nobody else's business

MESSAGING

- Text, with sent and delivered receipts
- Photos and videos from your gallery, or taken in the app
- Voice notes recorded in the chat, and audio files
- Large files sent in chunks with a progress bar
- Messages written while a device is away are queued and delivered the moment
it comes back
- A zoomable viewer for photos and video, with share and save

FINDING EACH OTHER

- Devices on the same Wi-Fi appear under Available on their own
- Pair by QR code: show the code on one device, scan it with the other
- Connect by IP, or scan your network, when a router blocks discovery
- Give paired devices your own private names, and a profile picture for others
to see

SECURITY

- Connections are encrypted with TLS, device to device
- Every device has its own key, remembered when you pair. Only the device you
paired with can reconnect; anything presenting a different key is refused
- Pairing shows a six-digit code on both screens. Matching numbers mean nothing
is sitting in between
- Scanning a QR code checks the key before it connects

PRIVACY

- No account, no sign-up, no phone number, no email
- We run no servers and collect nothing. There is nowhere for your messages to
be uploaded to
- No storage or photo permission. You pick files with Android's own picker,
which hands the app only what you chose
- Choose the name other devices see, so your phone's real name stays private
- The background service can be switched off whenever you like

GOOD TO KNOW

- Both devices must be on the same Wi-Fi network. Guest networks, extenders
running in router mode and routers with client isolation can stop devices
finding each other
- Messages are stored unencrypted on your own phone, protected by the Android
app sandbox and your device encryption
- Mobile data is never used for messaging

PERMISSIONS

- Camera: photos and video you send, and scanning QR codes
- Microphone: voice notes and video recording
- Notifications: new messages and pair requests
- Foreground service: staying reachable while the app is closed. Optional, and
switchable off in Settings