Sioyek is a PDF viewer with a focus on technical books and research papers.

Searchable
	Quickly search your previously opened documents, table of
	contents, bookmarks, and highlights.  Sioyek can even generate
	the table of contents if the document doesn't have one!

Smart Jump
	You can preview or jump to references (e.g. bibliography, figures,
	equations, etc.) even when the document doesn't have links.  You
	can also search references in google scholar with one click!

Portals
	You can create portals from parts of documents to other parts
	displayed in a second window.  So when you are reading a paragraph
	that is talking about a figure, table, algorithm, theorem, etc.
	you don't have to keep jumping between the two locations.

Marks and Bookmarks
	Mark locations with one-character symbols and then quickly jump
	back to them. You can also create bookmarks which are like marks,
	but use a descriptive text instead of a symbol and can be searched.

Keyboard Focused
	While sioyek fully supports many mouse actions, it is still
	possible to use sioyek only using a keyboard. This includes
	functionality such as text selection too!

Synctex
	Sioyek autoreloads the document so you can preview the changes
	as you edit the latex file. You can also jump between the
	corresponding locations in PDF and latex files with one click.

Other features include configurability, extensibility with external
commands and scripts, text highlighting, a discoverable command palette,
and a visual ruler highlighting the current line.