PDF Previews

Files.com previews PDF files by sending a PDF to the browser, where the built-in PDF.js viewer renders its pages.

When no automatic preview watermark is applied, Files.com sends the original PDF byte-for-byte. It does not convert the PDF into page images, strip PDF metadata, or remove embedded or non-rendered content before sending it to the browser. That data remains in the PDF received by the browser even when the viewer does not display it.

This also applies to users with List/Preview permission and visitors to preview-only Share Links. Those restrictions disable the normal download action, but do not prevent recipients from obtaining the PDF data sent to their browser. Remove any confidential metadata or hidden content from a PDF before making it available for preview.

When an automatic preview watermark is applied, Files.com generates a modified PDF copy containing the watermark and sends that copy to the browser. The stored original remains unchanged. Watermarking adds a visible mark; do not rely on it to remove metadata or other hidden content.

Thumbnails in file listings are separate preview images. Opening a PDF in the viewer transfers the PDF itself, or its watermarked copy, rather than only those thumbnail images.

The viewer does not support fillable forms or embedded PDF documents, and rendering issues can occur with some PDF files. PDF.js is a third-party engine, so we cannot accept bug reports related to PDF rendering. To view fillable form data, or when a PDF doesn't preview correctly, download the PDF and view it locally.

When integrations for online editing of standard business documents are disabled, previews for those document types are generated as PDF files, which can produce unexpected formatting.