TeXPortal is described as 'application to typeset TeX documents, targeting mainly at academic researchers' and is an app in the Education & Reference category. There are more than 25 alternatives to TeXPortal for a variety of platforms, including Windows, Linux, Mac, Haiku and Online / Web-based. The best alternative is LyX, which is both free and Open Source. Other great apps like TeXPortal are Overleaf (Freemium, Open Source), TeXstudio (Free, Open Source), Texmaker (Free, Open Source) and TeX Live (Free, Open Source).
LyX is a document processor that encourages an approach to writing based on the structure of your documents (WYSIWYM) and not simply their appearance (WYSIWYG). LyX combines the power and flexibility of TeX/LaTeX with the ease of use of a GUI.
TeXstudio is an integrated environment for writing LaTeX documents. Our goal is to make writing LaTeX as easy and comfortable as possible. Therefore TeXstudio has numerous features like syntax-highlighting, integrated viewer, reference checking and various assistants.
TeX Live is an easy way to get up and running with the TeX document production system. It provides a comprehensive TeX system with binaries for most flavors of Unix, including GNU/Linux, and also Windows.
Kile is a user-friendly TeX/LaTeX editor by KDE. Kile gives you the ability to use all the functionality of LaTeX in a graphical interface and has interactive preview mechanisms to readily see the results of editing.
TexMaths is an addon designed to provide LaTeX support into LibreOffice. LaTeX equations can be inserted as images (SVG or PNG formats) and the LaTeX code is saved into the image attribute for further editing.
The TeXworks project is an effort to build a simple TeX front-end program (working environment) that will be available for all today’s major desktop operating systems—in particular, MS Windows (XP and Vista), typical GNU/Linux distros and other X11-based systems, and Mac OS X.
VimTeX is a Vim plugin that provides support for writing LaTeX documents. It is based on LaTeX-Box and it shares a similar goal: to provide a simple and lightweight LaTeX plugin. It has been rewritten from scratch to provide a more modern code base.