Skim review
A focused, open-source Mac reader for searching, annotating, and organizing research PDFs.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Skim is a free, open-source PDF reader and note-taking application for macOS. It is designed for scientific papers while also supporting general PDF viewing, making it a strong fit for Mac users who need to search, mark up, navigate, and revisit research documents. The current release requires macOS 10.13 or later. Its core toolkit covers PDF viewing and text search, text and anchored notes, highlighting, underlining, strikeout, circles, boxes, freehand marks, and line annotations.
For research workflows, Skim offers several useful ways to organize and review documents. Bookmarks and table-of-contents navigation help with longer PDFs, while snapshots provide reference points during reading. Full-screen reading and presentations support focused review or presenting a document. PDF bundles store PDFs with notes, and notes can be exported as text. These features give Skim a narrow but coherent focus: reading, annotating, and carrying research notes into another workflow.
Its ecosystem fit is particularly relevant to technical and academic users. AppleScript supports automation, while LaTeX, SyncTeX, PDFSync, and BibDesk integrations connect Skim with document preparation, synchronization, and bibliography workflows. The trade-off is its limited scope: Skim is desktop software for macOS and does not provide OCR support. Choose it if you want an open-source Mac application centered on research PDF annotation and note handling. Consider another PDF reader if you need broader platform coverage or OCR.
Skim pros and cons
- Where it wins
- Extensive annotation tools, including highlights, shapes, and freehand marks
- Bookmarks, snapshots, presentations, and text-note export support research workflows
- AppleScript, LaTeX, SyncTeX, PDFSync, and BibDesk integrations
- Where it doesn't
- Available only for macOS
- No OCR support
- Focused on reading and annotation rather than broader PDF functions
Skim fact sheet, pricing and score →
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