diff --git a/backend/internal/data/repo/repo_item_attachments.go b/backend/internal/data/repo/repo_item_attachments.go
index 0cd2feed..f82a926e 100644
--- a/backend/internal/data/repo/repo_item_attachments.go
+++ b/backend/internal/data/repo/repo_item_attachments.go
@@ -98,11 +98,32 @@ func ToItemAttachment(attachment *ent.Attachment) ItemAttachment {
 }
 
 func (r *AttachmentRepo) path(gid uuid.UUID, hash string) string {
-	return filepath.Join(gid.String(), "documents", hash)
+	// Always use forward slashes for consistency across platforms
+	// This ensures paths are stored in the database with forward slashes
+	return fmt.Sprintf("%s/documents/%s", gid.String(), hash)
 }
 
 func (r *AttachmentRepo) fullPath(relativePath string) string {
-	return filepath.Join(r.storage.PrefixPath, relativePath)
+	// Normalize path separators to forward slashes for blob storage
+	// The blob library expects forward slashes in keys regardless of OS
+	normalizedRelativePath := strings.ReplaceAll(relativePath, "\\", "/")
+	
+	// Always use forward slashes when joining paths for blob storage
+	if r.storage.PrefixPath == "" {
+		return normalizedRelativePath
+	}
+	normalizedPrefix := strings.ReplaceAll(r.storage.PrefixPath, "\\", "/")
+	
+	// Trim trailing slashes from prefix and leading slashes from relative path
+	// to avoid double slashes when joining
+	normalizedPrefix = strings.TrimSuffix(normalizedPrefix, "/")
+	normalizedRelativePath = strings.TrimPrefix(normalizedRelativePath, "/")
+	
+	if normalizedPrefix == "" {
+		return normalizedRelativePath
+	}
+	
+	return fmt.Sprintf("%s/%s", normalizedPrefix, normalizedRelativePath)
 }
 
 func (r *AttachmentRepo) GetFullPath(relativePath string) string {
diff --git a/backend/internal/data/repo/repo_item_attachments_test.go b/backend/internal/data/repo/repo_item_attachments_test.go
index 0963a160..cbd839e5 100644
--- a/backend/internal/data/repo/repo_item_attachments_test.go
+++ b/backend/internal/data/repo/repo_item_attachments_test.go
@@ -10,6 +10,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"github.com/sysadminsmedia/homebox/backend/internal/data/ent"
 	"github.com/sysadminsmedia/homebox/backend/internal/data/ent/attachment"
+	"github.com/sysadminsmedia/homebox/backend/internal/sys/config"
 )
 
 func TestAttachmentRepo_Create(t *testing.T) {
@@ -281,3 +282,58 @@ func TestAttachmentRepo_SettingPhotoPrimaryStillWorks(t *testing.T) {
 	require.NoError(t, err)
 	assert.False(t, photo1.Primary, "Photo 1 should no longer be primary after setting Photo 2 as primary")
 }
+
+func TestAttachmentRepo_PathNormalization(t *testing.T) {
+	// Test that paths always use forward slashes
+	repo := &AttachmentRepo{
+		storage: config.Storage{
+			PrefixPath: ".data",
+		},
+	}
+	
+	testGUID := uuid.MustParse("eb6bf410-a1a8-478d-a803-ca3948368a0c")
+	testHash := "f295eb01-18a9-4631-a797-70bd9623edd4.png"
+	
+	// Test path() method - should always return forward slashes
+	relativePath := repo.path(testGUID, testHash)
+	assert.Equal(t, "eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png", relativePath)
+	assert.NotContains(t, relativePath, "\\", "path() should not contain backslashes")
+	
+	// Test fullPath() with forward slash input (from database)
+	fullPath := repo.fullPath("eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png")
+	assert.Equal(t, ".data/eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png", fullPath)
+	assert.NotContains(t, fullPath, "\\", "fullPath() should not contain backslashes")
+	
+	// Test fullPath() with backslash input (legacy Windows paths from old database)
+	fullPathWithBackslash := repo.fullPath("eb6bf410-a1a8-478d-a803-ca3948368a0c\\documents\\f295eb01-18a9-4631-a797-70bd9623edd4.png")
+	assert.Equal(t, ".data/eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png", fullPathWithBackslash)
+	assert.NotContains(t, fullPathWithBackslash, "\\", "fullPath() should normalize backslashes to forward slashes")
+	
+	// Test with Windows-style prefix path
+	repoWindows := &AttachmentRepo{
+		storage: config.Storage{
+			PrefixPath: ".data",
+		},
+	}
+	fullPathWindows := repoWindows.fullPath("eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png")
+	assert.NotContains(t, fullPathWindows, "\\", "fullPath() should normalize Windows paths")
+	
+	// Test empty prefix
+	repoNoPrefix := &AttachmentRepo{
+		storage: config.Storage{
+			PrefixPath: "",
+		},
+	}
+	fullPathNoPrefix := repoNoPrefix.fullPath("eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png")
+	assert.Equal(t, "eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png", fullPathNoPrefix)
+	
+	// Test with single slash prefix (like in tests)
+	repoSlashPrefix := &AttachmentRepo{
+		storage: config.Storage{
+			PrefixPath: "/",
+		},
+	}
+	fullPathSlashPrefix := repoSlashPrefix.fullPath("eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png")
+	assert.Equal(t, "eb6bf410-a1a8-478d-a803-ca3948368a0c/documents/f295eb01-18a9-4631-a797-70bd9623edd4.png", fullPathSlashPrefix)
+	assert.NotContains(t, fullPathSlashPrefix, "//", "fullPath() should not have double slashes")
+}