Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
AODocs - AODocs is the document management solution recommended for G Suite. Secure your documents, structure your content, & automate your processes
DjVuLibre - DjVuLibre: Open Source DjVu library and viewer
Docomotion - Docomotion offers tools for designing and generating all types of transactional and operational business documents.
DjView4 - Standalone viewer for DjVu files.
infoRouter - infoRouter is a EDMS that includes Workflow, Document routing, Electronic Forms, Scanning, Storage, Archiving, Indexing & Records Management