Alternatives to Skim
macOS PDF reader and annotator built for reading papers. The listings below can replace it for an important use case. Each note says what changes if you switch.
The original
Skim
macOS PDF reader and annotator built for reading papers.
Replacements
Listings that take over the same core job as Skim.
PDF Expert
Polished PDF reader and editor for macOS and iOS.
PDF Expert adds an iOS version and genuine text and image editing, but it is closed source and editing, OCR and conversion require a paid subscription or licence.
Sioyek
A PDF reader built for textbooks and research papers, with keyboard control and quick jumps to figures and references.
Sioyek is open source on macOS, Windows and Linux with figure and reference overlays and LaTeX search, but its keyboard-first design has a learning curve.
Adobe Acrobat
Adobe's PDF software: the free Acrobat Reader for viewing and commenting, and paid Acrobat plans for editing and conversion.
Adobe Acrobat Reader is free on macOS, Windows, web and mobile with commenting and Fill & Sign, but it is proprietary and editing needs a paid plan.
Okular
Universal document viewer for PDF, EPUB, comics, DjVu and more.
Okular is open source on macOS, Windows and Linux, opens EPUB, comics and DjVu, and keeps annotations separate, but pulls in KDE libraries.
Foxit PDF Reader
Free PDF reader with annotation, form filling and signing.
Foxit PDF Reader gives free annotation, form filling and signing on desktop and mobile, but it is closed source and its interface promotes paid products.
MuPDF
Compact, very fast PDF and XPS viewer with a command-line toolkit.
MuPDF is an extremely fast open-source viewer across desktop and mobile with a command-line toolkit, but its interface is minimal and lacks SyncTeX-focused paper tools.
Also worth comparing
These listings name Skim as their own alternative, so the relationship runs both ways.
Highlights
A PDF reader for Mac, iPad and iPhone that turns annotations into exportable notes.
Skim is a free open-source macOS reader for papers with SyncTeX support, but it has no iOS app and stores notes in its own format.
LiquidText
An active-reading app for annotating PDFs and pulling excerpts into a flexible workspace.
Skim is a free, open-source macOS reader with annotation and snapshot tools for academic papers, lacking a flexible excerpt workspace.
PDF Tools
Emacs package for viewing, searching and annotating PDF files inside the editor.
Skim is a standalone macOS reader and annotator with SyncTeX integration for LaTeX, working outside Emacs but only on macOS.
Preview
Apple's built-in macOS app for viewing, annotating, merging and signing PDFs and images.
Skim is a free open-source macOS reader focused on papers and LaTeX via SyncTeX, but it does not handle images and stores notes in its own format.
zathura
A minimal, keyboard-driven document viewer with plugin support for PDF, PostScript and DjVu.
Skim is a macOS-only open-source reader with SyncTeX integration for LaTeX and annotation tools for academic papers.
Similar software
Related functionality, not a direct replacement.
Mendeley
A reference manager from Elsevier for collecting, annotating and citing research papers.
Xournal++
Handwritten notes and PDF annotation with a stylus, including on top of lecture slides and scanned papers.
Explainpaper
A web tool that explains highlighted passages of uploaded research papers in plain language.
ChatPDF
An AI tool that summarizes PDFs and answers questions about them, with citations to the source.
ReadCube Papers
A reference manager and PDF reader for organizing, annotating and citing research papers.
MarginNote
A study app for Mac and iPad that links PDF highlights, mind maps and flashcards.
