ChemRxiv is a very popular preprint server for the Chemistry field. As the name suggests, it’s inspired by ArXiv, BioRxiv.
However, I note that Paperpile doesn’t recognise the ChemRxiv website format: it doesn’t have the “Add to Paperpile” Chrome button, and instead has the “Add this website as a reference” message. And once added, it usually struggles to download the PDF, requiring to do this manually.
I’ve used the option “Report this page”, and messaging here too, in order to ask if ChemRxiv could be recognised by Paperpile for smooth interaction.