How we decide.
Every status on WorksOnDuo is a claim about how an app looks on iPhone Duo’s inner display. Here’s what each one means and what we need before we make it.
Last updated October 23, 2026
Statuses
| Status | Meaning |
|---|---|
| Built for Duo | Full screen, with layouts or features designed for the fold. |
| Full screen | Fills the inner display. No Duo-specific features yet. |
| Partly adapted | Uses most of the inner display, with some empty space. |
| Black bars | Runs in a phone-sized window with black borders. |
| Not confirmed yet | No reliable information yet. Seen it? Tell us. |
We describe the inner display only. On the outer display every iPhone app behaves as it does on any other iPhone, and every app can take part in Split View automatically.
Evidence and confidence
No app leaves “Not confirmed yet” without at least one piece of public evidence. We record the strongest source on each page:
| Confidence | What it means |
|---|---|
| Verified on device | We checked it ourselves on an iPhone Duo. |
| Developer confirmed | The developer said so publicly or in release notes. |
| Shown by Apple | Apple demonstrated or described this app on iPhone Duo. |
| Community reports | Several consistent, reviewed reports from iPhone Duo owners. |
| From release notes | Inferred from the app's release notes; not yet seen on device. |
| From the app's build | Read from the app's App Store package: the iOS SDK it was built with decides how Apple shows it on the inner display. |
| No evidence yet | Nobody has confirmed how this app behaves on iPhone Duo. |
Where the evidence comes from
We check every tracked app every day, from these sources, strongest first:
- Apple. Apps Apple names or demonstrates on iPhone Duo, such as its October 22 launch roundup.
- The developer. Release notes or posts saying the app supports or is optimized for iPhone Duo, and App Store listings that include screenshots made for iPhone Duo’s inner display. Developers only upload those for apps they designed for it.
- The app’s build. Apple decides how an app looks on the inner display from the iOS SDK it was built with: iOS 26 or earlier gets a phone-sized window with black bars, iOS 27.0 gets more of the screen with some space left over, and iOS 27.1 or later can use all of it. We read that SDK version from the app’s App Store package each time it updates. This is how we can say an app is not adapted yet without an iPhone Duo in hand.
- Owners and press. Reviewed reports and screenshots from people using iPhone Duo, and hands-on coverage.
If two sources disagree — say, release notes claim support but the build uses an older SDK — the build wins and a person reviews it.
Rules we follow
- No guessing. We don’t infer a status from an app’s popularity, its developer or its minimum iOS version — only from the sources above.
- People review the edge cases. Our daily scan sets statuses from developer statements, Duo screenshots and build data automatically. Conflicts, and release notes that mention iPhone Duo without claiming support, go to a person.
- Owner reports need agreement. We need several consistent, reviewed reports — ideally with screenshots — before marking a status from the community.
- Negative statuses need evidence too. We don’t label an app “Black bars” without a report or test showing it.
- Everything is dated. Each page shows when it was last checked and keeps a history of status changes.
- Money never changes a status. Sponsorship, if any, is labelled and has no effect on the data.
Which apps we track
The US App Store’s top free, top paid, top grossing and top free games charts, refreshed daily, plus a hand-picked list of apps people are most likely to ask about (banking, social, streaming, productivity, AI assistants and popular games). Once an app has a page, we keep it. Missing one? Ask us to track it.
Facts from the App Store
App names, icons, developers, versions, release notes, and whether an app has an iPad version come from Apple’s public App Store data. “iPad version” means the developer ships a layout for iPad, not just the compatibility mode every iPhone app gets.
Corrections
Developers and owners can submit a correction or email us. We aim to respond within 48 hours and note the change in the app’s history.