The UWP code to migrate

About the app (optional, but it changes the answer)

Two facts most findings turn on:

Migrating

Findings

Migrated code

What changed

Your paste on the left of the marker, the rewrite on the right — computed in your browser from the result you already have, so it costs nothing.

How it works

Nothing to paste? — a UWP editor page with the usual suspects in it: a MessageDialog, a dispatcher call, a picker with no window handle. Or , rendered from a saved reply with no run and no charge.

Paste the file, not a description

C#, XAML or both. The legacy-API scan runs in your browser as you type — free, no sign-in, nothing sent anywhere — and flags each known trap with its line and its replacement.

Say how the app is built

Packaged or unpackaged, one window or several — the right migration for pickers, dialogs and settings depends on it. What you leave out comes back as an open question.

Take the code, then the checklist

The rewrite keeps your identifiers, comments and logic — only the APIs move. Then read Manual steps: a verdict of Drop-in rewrite is only allowed when that list is empty.

The UWP to WinUI 3 API map

UWP	WinUI 3 / Windows App SDK