PDF apps for Mac and iPhoneHead to head
PDF Expert vs Skim
PDF Expert ranks #1 and Skim ranks #2 in our guide to the best PDF apps for Mac and iPhone. PDF Expert is our pick for most people, and Skim is the best free option.
PDF ExpertPick PDF Expert if you fix, sign or redact PDFs for work on a Mac, iPad or iPhone.Free to startBest free
SkimPick Skim if you read long papers or textbooks on a Mac and want your highlights in 1 list.Free, open sourceWhat decides it
- Skim costs less over 3 years: Free, against $139.99 for PDF Expert.
- Both run on Mac. Only PDF Expert runs on iPhone and iPad.
Side by side
Prices are checked every day.
| At a glance | PDF Expert | Skim |
|---|---|---|
| Price | Free to read, mark up and sign. Premium is $49.99 a year, or $139.99 once on Mac | Free and open source |
| How you pay | Free, with paid upgrades | Free |
| 3 years of use | $139.99 | Free Cheaper |
| Free trial | Free to start | Free to start |
| Runs on | Mac, iPhone, iPad | Mac |
| Where to buy | Developer, App Store | Developer |
| Rating | 4.7 216K ratings | Too few ratings |
| Features | Free trial | Open source |
| Made by | Readdle Technologies Limited | Not listed |
| Last updated | 22 Oct 2026 | Not tracked |
Who should get which
Get PDF Expert if
You fix, sign or redact PDFs for work often enough that Preview keeps falling short.
Get Skim if
You read and mark up long PDFs, like research papers or textbooks, and want your notes in one list.
Skip PDF Expert if
You open the odd PDF to read or sign it, which Preview and iPhone Markup do free.
Skip Skim if
You open the occasional PDF to sign or skim, and Preview already does highlights and notes.
Our verdicts
PDF Expert
Free for reading, highlighting, filling out forms and signing, PDF Expert covers what most people do with PDFs on Mac, iPhone and iPad before asking for money. Editing the actual text and images, redacting, merging, OCR and Word or Excel conversion need Essential at $49.99 a year, or $139.99 once on the Mac alone. If you only read and annotate on a Mac, Skim does that free and open source.
Skim
Preview handles a quick highlight, but Skim is built for reading long papers: one swipe highlights, and every note and highlight collects in one list you can export as text. A reading bar, snapshots that keep a figure in view and SyncTeX for LaTeX writers round it out. It's free and open source, and it's a reader rather than an editor, so changing a PDF's text is PDF Expert's job.
What each one helps you do
PDF Expert
- Fix a typo inside a PDF without the original
- Sign and send a contract from your iPhone
- Merge scanned pages into one file
- Shrink a big PDF so it fits in email
Skim
- Highlight a PDF with one swipe
- Export all your notes from a paper
- Keep a figure in view while reading
- Jump from a PDF to your LaTeX source
Where to get them
PDF Expert
Free to read, mark up and sign. Premium is $49.99 a year, or $139.99 once on Mac
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From the developerEvery paid plan has a 30-day money-back guaranteeFree downloadGet it
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App Store, iPhone and iPadWith in-app purchasesFree downloadApp Store
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Mac App StoreWith in-app purchases$139.99Mac App Store
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Neither one quite right?
The other picks in our guide to the best PDF apps for Mac and iPhone.
Read the full guideAll PDF Expert alternativesAll Skim alternatives