mpdf is a php library to convert html to pdf, supports css and more.
Why? In my case, wkhtmltopdf doesn work on some servers, tried a console execution with no luck.
mpdf is multi-platform, entirely a php library, works very good, barcode support, etc etc
An a plus, is lightweight than wkhtmltopdf.
wkhtmltopdf folder 73mb
mpdf folder 32mb
And mpdf will work even as a replacement to tcpdf and no need of java libraries