How to publish your flutter mobile app on App Store, PlayStore and even Microsoft Store

1. Create Developer Accounts: Register for a developer account on each platform:
• Microsoft Developer Center: https://partner.microsoft.com/
• Apple Developer Program: https://developer.apple.com/programs/
• Google Play Console: https://play.google.com/console/
Note that there are registration fees for each platform. $99/year for Apple, $25 one-time fee for Google, and a one-time fee of $19 for individual developers.

2. App Signing: Sign your app using the appropriate method for each platform. For Windows, you'll use a certificate from the Windows Dev Center. For iOS, you'll create a distribution certificate and provisioning profile through the Apple Developer portal. For Android, you'll generate a keystore file and sign your app using Android Studio or command line tools.

3. App Store Guidelines and Policies: Ensure your app complies with each platform's guidelines and policies:
• Microsoft Store Policies: https://docs.microsoft.com/en-us/windows/uwp/publish/store-policies/
• Apple App Store Review Guidelines: https://developer.apple.com/app-store/review/guidelines/
• Google Play Developer Policies: https://play.google.com/about/developer-content-policy/

4. Prepare App Store Listing: Prepare the metadata and promotional materials for your app listing. This typically includes app icons, screenshots, videos, descriptions, and other required details.

Windows Store (Microsoft Store):

1. Develop your app: Build your app using Visual Studio or another compatible development environment. Make sure it meets the store's app certification requirements: https://docs.microsoft.com/en-us/windows/uwp/publish/app-certification-requirements.

2. Package your app: Create an app package (.appx or .msix) using the Windows Application Packaging Project in Visual Studio.

3. Submit your app: Log in to the Microsoft Partner Center (https://partner.microsoft.com/dashboard), create a new app submission, provide the required information, and upload your app package.

4. Publish and manage your app: After submission, your app will be reviewed by Microsoft. If it passes the review, it will be published in the Windows Store.

App Store (Apple):

1. Create a developer account: Sign up for an Apple Developer account at https://developer.apple.com/programs/.

2. Develop your app: Build your app using Xcode, the official development environment for iOS and macOS apps.

3. Prepare your app for distribution: Follow the guidelines for App Store distribution, including configuring your app, creating an App ID, and generating provisioning profiles. More information can be found here: https://help.apple.com/xcode/mac/current/#/dev60b6fbbc7.

4. Submit your app: Use Xcode to submit your app to App Store Connect (https://appstoreconnect.apple.com/). Provide required information and assets, such as app description, keywords, screenshots, and pricing.

5. Publish and manage your app: After submission, your app will be reviewed by Apple. If it passes the review, it will be published in the App Store.

Google Play Store:

1. Create a developer account: Sign up for a Google Play Developer account at https://play.google.com/apps/publish/signup/.

2. Develop your app: Build your app using Android Studio, the official development environment for Android apps.

3. Prepare your app for release: Generate a signed APK or Android App Bundle (AAB) file. More information on this process can be found here: https://developer.android.com/studio/publish.

4. Submit your app: Log in to the Google Play Console (https://play.google.com/console), create a new app, provide the required information, and upload your APK or AAB file.

5. Publish and manage your app: After submission, your app will be reviewed by Google. If it passes the review, it will be published in the Google Play Store.