Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
LaTeXML - In brief, latexml is a program, written in Perl, that attempts to faithfully mimic TeX’s behaviour...
TeXstudio - TeXstudio is an integrated environment for writing LaTeX documents.
latex2html - latex2html is a convertor written in Perl that converts LATEX documents to HTML. This way e.g.
LyX - LyX is a document processor.
tex2mail - tex2mail – Converts TeX to mailable "ASCII art"