Skim
Skim: A focused, open-source Mac reader for searching, annotating, and organizing research PDFs. Ranked #10 of 23 in PDF Readers by our editors (8.4/10); pricing: Free plan; best for mac users reading and annotating research PDFs.
At a glance
- Editor score8.4 / 10
- PricingFree plan
- Best forMac users reading and annotating research PDFs
- Free planYes
- Paid fromFree
- Facts checked24 Sep 2026
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
Our verdict on Skim
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.
Your product? Our editors can test Skim in depth and publish a review, labelled as paid · from $149/mo →
Skim pricing
Skim fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Annotation tools | Yes |
| OCR support | Not verified |
| Form filling | Not verified |
| Offline access | Not verified |
| Text-to-speech | Not verified |
| Platform support | Desktop |
| Deployment | Desktop |
| Platforms | macOS |
| Support | Community |
| Built for | Solo, Small business (editorial estimate) |
| Integrations | 4 integrations: LaTeX, SyncTeX, PDFSync, BibDesk |
| Pricing | Free plan |
| Website | skim-app.sourceforge.io |
| Facts checked | 24 Sep 2026 |
Skim integrations
Skim lists 4 integrations on its own site.
- LaTeX
- SyncTeX
- PDFSync
- BibDesk
Alternatives to Skim
- Foxit PDF ReaderA free cross-platform reader with collaboration, forms, signatures, and cloud integrations.9.4
- OkularA capable open-source desktop reader with annotations, forms, signatures and accessibility tools.9.2
- PreviewA capable free PDF reader for Apple users, with practical editing and signing tools.9.1
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The editor score above is our own research. What this page doesn't have yet is a reader's view — what you used Skim for, what worked and what didn't. No stars are seeded and no review is paid for; an editor reads every one before it appears.
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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