Okular

Overview

Okular is a free and open-source multi-platform document viewer developed by the KDE community. It lets you read, navigate, annotate, and manage a large variety of document and image formats with advanced tools like bookmarks, thumbnails, annotations, and digital signature support.

Key features

• PDF support
• EPUB & eBook formats
• Comic book reading (CBR/CBZ)
• Images & Markdown preview
• Annotations & notes
• Bookmarks & thumbnails
• Digital signature verification
• Cross-platform support