By default BookStack uses Dompdf to export pages as PDF documents. The benefit of using DomPDF is that it doesn’t require any additional installation or setup but the rendering capabilities are somewhat limited.
As an alternative you can use wkhtmltopdf to generate PDF documents instead. wkhtmltopdf uses the Qt WebKit rendering engine to provide a more accurate overall result.
Pre-compiled binaries for wkhtmltopdf can be found on the downloads page of their website. BookStack will check for a file named
wkhtmltopdf at the base folder of a BookStack install. If found it will use that to render PDF’s. If that does not exist it will check for a
WKHTMLTOPDF variable in the
.env file. You can use this variable to set an alternate location to wkhtmltopdf:
# In .env file WKHTMLTOPDF=/home/user/bins/wkhtmltopdf
If neither of those exist Dompdf will be used instead.