Designing for the screen

Zend opens your app full screen.

A WebView with no URL bar or browser chrome.
Zend shows your icon and name while you load.
The status bar matches your page’s body background colour.
Zoom and link callouts are off.
One small floating pill (top right, collapses to a dot, draggable) gives the user Close and Report.
Android back goes back through your pages first.

Unreviewed apps show “Made by . Not checked by Zend.” on the loading screen and in the menu.

Guidelines

Build for full screen, mobile first. Set a solid body background colour.
Keep the top-right 120×44 px clear of important controls. The Zend pill sits there until it folds.
Don’t add your own “back to Zend” button. Call zend.close() when you’re done; the optional result goes back to whatever opened you.
Links to other sites open outside Zend after the user confirms. Keep everything you need on your own origins.
Users find you on Discover by name. Use your real app name in name and a one-line description.
Let users report problems with zend.report({ reason, detail?, interactionId?, prizeId? }). Reasons: scam, unfair_result, offensive, broken, other.

Zend loads your page in a frame on the web. If you send a Content-Security-Policy, allow Zend as a frame ancestor:

Content-Security-Policy: frame-ancestors https://app.usezend.app

Public apps also serve /.well-known/zend-app.json on every origin. See Public apps.