BackupKit

Kotlin Multiplatform backup into the user's own cloud: iCloud on iOS (CloudKit or iCloud Drive), the Google Drive app-data folder on Android. No server, no account on your side, no OAuth client setup on iOS.

Start here

1. Setup, iOS: one entitlement, and the CloudKit schema step for Production builds.
2. Setup, Android: a Google Cloud OAuth client and the one-time consent dialog.
3. The quickstart on the README, then restore on first launch.

Guides

• Support matrix: the three transports side by side.

• The SyncEngine contract: the ten guarantees.

• Restore on first launch: probe, hold, download, place, resume.
• Android consent, once.
• Errors: the seven CloudError values and the user copy for each.
• Bring your own scheduler.
• Recipes: SQLDelight, Room, a folder of photos, encrypt before upload.
• FAQ and known issues.
• Stability and versions.

Reference

• API reference (Dokka), binary API tracked in backupkit/api.
• Design and publishing, for maintainers.