I like the simplicity of PDF Viewer https://pdfviewer.io/. Source: over 1 year ago

And where I just want a clean, no subscription required PDF viewer that has consistent annotation tools, I use PDF Viewer (macOS, iOS/iPadOS): https://pdfviewer.io. Source: about 2 years ago

Mac OS X 10.7 Lion: the Ars Technica review | Ars TechnicaRevert changes to PDFs and images in Preview on Mac - Apple SupportTitlebar Renaming (Screenshot)General Preference Pane (Screenshot)Pixelmator ProAcorn 7PDFpenPDF ViewerLiquidTextiOS 8 Screenshot Reveals New Healthbook, Preview and TextEdit Icons - MacRumors. Source: over 2 years ago

Please see under features for more. Zotfile and a quick search gives you other options as well: https://libguides.libraries.wsu.edu/c.php?g=768677&p=5514204#s-lg-box-17429213. Source: 12 months ago

Not web based (not actually hosted), but an open source desktop client that can be used with a (self hosted) file sync method of choice using Zotfile (http://zotfile.com/). Source: about 1 year ago

Check out zotfile for Zotero. It allows you to use any cloud to host your article. I use it with our university sponsored onedrive http://zotfile.com. Source: about 1 year ago

The Zotfile plugin is a thing too if you don't want to pay for Zotero storage. You can use its 'send to tablet' feature to automate some of the pushing and pulling between Zotero and an Android tablet and extract the annotations. Here is a guide. Source: about 1 year ago

ZotFile is also an amazing PDF management add-on for Zotero. Source: about 1 year ago