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Skim

Free#13 of 23 in PDF Readers

Skim: A focused, open-source Mac reader for searching, annotating, and organizing research PDFs. Ranked #13 of 23 in PDF Readers by our editors (6.3/10); pricing: Free plan; best for mac users reading and annotating research PDFs.

6.3/10Editor score
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Skim6.3 Visit Skim

At a glance

  • Editor score
    6.3 / 10
  • Pricing
    Free plan
  • Best for
    Mac users reading and annotating research PDFs
  • Free plan
    Yes
  • Paid from
    None
  • Facts checked
    24 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.

Skim pricing

Plans Free planFree Free to use — no paid tier required for the core job.
See plans on skim-app.sourceforge.io

Skim fact sheet

Free planYes
Paid fromNone
Annotation toolsYes
OCR supportNot verified
Form fillingNot verified
Offline accessNot verified
Text-to-speechNot verified
Platform supportDesktop
DeploymentDesktop
PlatformsmacOS
SupportCommunity
Built forSolo, Small business (editorial estimate)
Integrations4 integrations: LaTeX, SyncTeX, PDFSync, BibDesk
PricingFree plan
Websiteskim-app.sourceforge.io
Facts checked24 Sep 2026

Skim integrations

Skim lists 4 integrations on its own site.

  • LaTeX
  • SyncTeX
  • PDFSync
  • BibDesk

Alternatives to Skim

See all Skim alternatives →

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Featured on iTechGuides

Featured on iTechGuides — Skim 6.3/10

Skim is listed in our PDF Readers directory. Add the badge to your site — it links back to this page.

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Guides on PDF readers

Reviewed by iTechGuides Editors · Editorial team · Updated Sep 2026

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