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Gumnut automatically avoids storing an exact duplicate more than once in the same library. This applies whether you upload through the Gumnut web app, an Immich app, the REST API, an SDK, or an AI assistant.

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What Counts as a Duplicate

Gumnut compares the contents of each uploaded file using a SHA-256 checksum. A file is a duplicate when its bytes exactly match a file that already exists in the target library. Renaming a file or changing its filesystem timestamps does not create a new copy as long as the file contents stay unchanged. Upload metadata such as the source device identifier is not used to decide whether files are duplicates. Files that look alike but have different bytes are separate assets. For example, Gumnut does not currently group or remove:
  • Edited, cropped, or resized copies
  • Re-encoded versions of the same photo or video
  • Screenshots of an existing photo
  • Similar burst photos

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What Happens When You Upload a Duplicate

Gumnut keeps the existing asset and does not store a second copy or charge its bytes against storage again. The existing asset keeps its current metadata. Duplicate detection is scoped to a library. If your account has multiple libraries, the same file can exist once in each library. When you upload directly to an album, Gumnut can add the existing asset to that album without creating another library copy. If the asset is already in the album, the album membership is left unchanged.
For API clients, POST /api/assets returns 201 Created for a new asset and 200 OK with the existing asset when the upload is an exact duplicate. Storage limits are checked first, so an account or library already at its storage cap receives 507 Insufficient Storage even for a duplicate upload.

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Duplicates in Trash

Trash remains part of the library until an asset is permanently deleted. If an upload matches an asset in Trash, Gumnut returns that trashed asset instead of creating or restoring it. Restore the asset from Trash if you want it to appear in your library again.

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Duplicate Management

Gumnut does not currently provide a duplicate-management view for finding and reviewing visually similar assets. Automatic upload deduplication only prevents additional copies of files whose contents match exactly.