OneDrive Bidirectional Sync

Synchronize Obsidian vault files across Windows, Linux, macOS, iOS, and Android through a private OneDrive app folder. The plugin communicates directly with Microsoft Graph and does not require the OneDrive desktop client.

Features

• Uses the least-privileged Microsoft Graph Files.ReadWrite.AppFolder permission.
• Uploads and downloads file changes between multiple devices.
• Propagates file deletions in both directions.
• Preserves a local conflict copy when the same file changed on both sides.
• Supports automatic synchronization at a configurable interval.
• Excludes .obsidian by default to avoid syncing device-specific settings and the plugin's authentication data.

Important safety information

This plugin is an early release. Back up your vault before the first sync. Avoid editing the same file on multiple devices at the same time.

Authentication tokens are stored in the plugin's local Obsidian data file. Never share that file. The plugin always excludes its own data.json from synchronization.

Installation

Install the plugin from the Obsidian community plugin directory when available. For manual installation, place manifest.json and main.js in:

<vault>/.obsidian/plugins/onedrive-bidirectional-sync/

Then reload Obsidian and enable OneDrive Bidirectional Sync under Community plugins.

Microsoft Entra application setup

Each user currently needs a Microsoft Entra application registration:

1. Create an application registration in the Microsoft Entra admin center.
2. Select the account type that supports organizational directories and personal Microsoft accounts.
3. Enable Allow public client flows under Authentication.
4. Add the delegated Microsoft Graph permission Files.ReadWrite.AppFolder.
5. Enter the application's Application (client) ID in the plugin settings.

All devices must use the same client ID, Microsoft account, and vault ID.

How synchronization works

Remote files are stored under the application's private OneDrive app folder:

OneDrive/Apps/<application name>/vaults/<vault ID>/

The plugin stores a local synchronization snapshot and compares it with local file metadata and OneDrive item ETags. A one-sided change is propagated to the other side. If both sides changed, the local version is preserved as a conflict copy and the remote version replaces the original path.

Current limitations

• Simple uploads support files up to 250 MB.
• Initial synchronization resolves different same-path files using modification time. Upload from the primary device before connecting additional devices.
• iOS and Android may suspend background timers. Sync after opening Obsidian or run the manual sync command.
• Microsoft Graph delta queries, resumable uploads, end-to-end encryption, and automated integration tests are not yet implemented.

Development

pnpm install
pnpm typecheck
pnpm build

References

• Microsoft Graph OneDrive app folder
• Microsoft identity platform device authorization grant
• Microsoft Graph upload or replace file contents

License

MIT