Updated 6-8-18
- Adobe Reader–free
- Annotat8–lots of options; free
- DocHub–
- Easy Annotate–partnered with Dropbox and Google Drive; annotate side-by-side PDFs
- Foxit
- Goodreader–fee
- iAnnotate–fee; open Google Drive documents in iAnnotate
- iOS Mail App for iPads and iPhone (built in–limited tools, but useful)
- Kami–open PDF in Google Drive, then open with Kami (app)
- Lumin–open PDF in Google Drive, then open with Lumin (app)
- Notability
- Pinpoint–mark up screenshots; free
- PointOut–zooms in on a screenshot
- Skitch–annotate screenshots
- SlingNotes–fee
