Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
Adobe Reader - Adobe Acrobat Reader is a free tool for viewing documents that have been stored in Adobe's Portable Document Format (PDF).
TeXworks - The TeXworks project is an effort to build a simple TeX front-end program (working environment)...
SysTools OST Viewer - Free Outlook OST Viewer Software is used to open OST file with attachments. OST Reader Tool provide a complete solution to view corrupted, orphaned OST files.
Texmaker - Texmaker, free cross-platform latex editor
PDF Reader Pro - PDF Reader Pro is an all-in-one PDF office supporting to Read, Annotate, Edit, OCR, Convert, Create & Fill Form, Sign PDFs, TTS on Mac, iOS, Android, and Windows.