PDF Annotator vs Skim (2026): which should you pick?

Pick PDF Annotator if

• Fits if you mark up and sign PDFs by pen on Windows
• Works for people who measure on plans in PDFs

Look elsewhere if

• Skip it if you use a Mac or phone, as it is Windows only
• Not for you if you need to edit existing text, which the pages read do not list
• Watch out: the license covers version 10, and a later major version needs an upgrade or Upgrade Assurance at $39.94
• Watch out: prices exclude VAT and volume pricing needs a quote

Pick Skim if

• Fits if you read and mark up papers on a Mac, especially with LaTeX or BibDesk
• Works for anyone who wants a free annotator and not an editor

Look elsewhere if

• Skip it if you use Windows, Linux or a phone, as it runs on Mac only
• Too light for editing text or filling in forms, since neither is listed
• Watch out: support is a wiki, mailing lists and bug trackers, not a help desk
• Tight if your Mac is old, because the current version needs macOS 10.13

PDF Annotator

• It runs on Windows only; there is no Mac, mobile or browser version.
• The license covers version 10; a later major version needs an upgrade purchase or Upgrade Assurance.
• Prices exclude VAT, and volume pricing needs a quote for purchase orders.
• It is built for marking up and organizing pages, and the pages read do not list editing of existing text.

Skim

• Mac only; current version 1.7.19 needs macOS 10.13 or higher, with older versions listed for older systems.
• It is a reader and annotator, with no listed tools for editing existing text or filling in forms.
• Support runs through a wiki, mailing lists and bug trackers rather than a company help desk.

PDF Annotator

Pen, text and highlighter

Write by hand or type comments directly on a PDF, and mark passages with a text marker.

Shapes, stamps and images

Arrows, lines, rectangles and circles, more than 330 predefined stamps, date and signature stamps, and inserted images.

Measuring tools

Dimension distances and areas and measure angles on PDF plans or technical drawings.

Formula editor

Creates and edits scientific formulas, with LaTeX support.

Create and combine PDFs

A virtual PDF printer creates PDFs from other applications, and pages can be inserted, merged and reordered.

Full-screen presentation

Presents PDFs full screen, with annotation tools available while presenting.

Skim

Notes and highlights

Add and edit notes, highlight text with one-swipe modes, and view all notes and highlights in one list.

Snapshots and reading bar

Keep snapshots of other parts of a document for reference and focus a line at a time with a reading bar.

Navigation

Move around with the table of contents or thumbnails, with a visual history and previews of internal links.

Presentations

Present a PDF full screen with built-in transitions, and crop pages with the smart cropping tools.

Export and scripting

Export notes as text and automate with extensive AppleScript support.

LaTeX and reference tools

Works with LaTeX through SyncTeX and PDFSync, and integrates with BibDesk and other third-party apps.

PDF Annotator

• License$79.95

  one-time per user, for 1 to 4 users

  Perpetual license for version 10 with free updates within that version; volume prices fall to $23.95 per user at 1,000 or more.

• Upgrade Assurance$39.94

  for 2 years per user, one-time

  Optional add-on covering 2 years of all updates, including major ones, and priority support tickets.

Skim

• Skim$0

  Free to download; the site lists no paid plans or licence fees.

PDF Annotator

• Education

  Student and faculty licenses

  The shop page has separate Student Licenses and Faculty Licenses tabs; prices are shown there.

Skim

No public discounts listed.