When using the advanced options for generating PDFs you have the option to include thumbnail images and other PDFs included. Generating PDFs that include other PDF information can be computationally intensive. The following limits apply:
Generate Image Thumbnails
There are no predefined limits as to what the PDF engine will attempt to embed into a PDF. As a fail-safe, if a PDF cannot be generated with the image, it will simply exclude it. For best results
The original image size should be less than 25 MB
No more than 20 images should exist in a single application
Merge Uploaded PDFs
There are no predefined limits as to what PDFs the engine can merge. As a fail safe, if a PDF cannot be merged, the PDF generation will continue without the document. For best results:
Individual PDFs should not be more than 25 MB
No more than 20 PDFs should exist in a single application
The uploaded PDFs should not be password protected or use digital signatures
Merge Uploaded Word Docs and PowerPoint Presentations
Office documents are first converted to PDF using the open source LibreOffice library. Formatting and fonts may not match the original documents. In some cases documents may not merge at all if LibreOffice cannot read them. The intended use case is to merge letters of reference written in Word instead of PDFs, however the engine seems to work in a majority of cases when a file meets the following:
File is less than 10 MB
File is not password protected
File is generated using Microsoft Office 365 on PC or Mac