
Description: Okular is a versatile document viewer software for KDE. It supports viewing PDFs, EPUBs, ODT, and other document formats. Okular allows annotating, highlighting, commenting on documents as well as filling forms.
Type: Open Source Test Automation Framework
Founded: 2011
Primary Use: Mobile app testing automation
Supported Platforms: iOS, Android, Windows

Description: PDF-XChange Viewer is a free PDF reader and editor for Windows. It provides basic PDF viewing and annotation features like adding text notes, highlights, shapes, freehand drawing, and more.
Type: Cloud-based Test Automation Platform
Founded: 2015
Primary Use: Web, mobile, and API testing
Supported Platforms: Web, iOS, Android, API