Umbraco File Upload Preview

This one handles custom file upload previews in the Umbraco backoffice when you need something beyond the default thumbnail behavior. You define which MIME types to target (PDFs, audio files, whatever), then build a Lit element that renders your preview during the upload flow. The skill pulls fresh docs from the official Umbraco site and generates both the manifest and element implementation. Honestly most useful when you're dealing with specific file types that need context before they hit the media library, like showing waveforms for audio or custom icons for proprietary formats. It implements the UmbFileUploadPreviewElement interface and manages object URLs properly so you don't leak memory.

skills.sh installs: 396
GitHub stars: 27
last updated: Aug 21, 2026

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Install

$ npx -y skills add umbraco/umbraco-cms-backoffice-skills --skill umbraco-file-upload-preview --agent claude-code

Installs into .claude/skills of the current project.

Files

Umbraco File Upload Preview

What is it?

File Upload Previews are custom web components that render previews for specific file types during upload in Umbraco. They allow you to create visual representations for files based on their MIME types, such as displaying thumbnails for images, waveforms for audio, or custom icons for specific file formats.