File Extension Validation

Restrict uploads to specific file types using the asp-extensions attribute. Files that do not match the allowed extensions are rejected immediately on the client side before any upload begins.

What you should see: only .jpg/.png/.gif/.webp are accepted, up to 5 MB. Choose a .pdf and it is refused immediately, before any request is made.

Images Only (.jpg, .png, .gif, .webp)

Drag & drop files here, or paste from clipboard

Documents Only (.pdf, .doc, .docx, .xls, .xlsx)

Drag & drop files here, or paste from clipboard

<!-- Images only -->
<core-upload asp-upload-url="/api/upload/upload"
 asp-extensions=".jpg,.png,.gif,.webp"
 asp-max-size="5MB"
 asp-button-text="Select Images">
</core-upload> 
<!-- Documents only -->
<core-upload asp-upload-url="/api/upload/upload"
 asp-extensions=".pdf,.doc,.docx,.xls,.xlsx"
 asp-max-size="20MB"
 asp-button-text="Select Documents">
</core-upload>