https://detexify.kirelabs.org/classify.htmlTeX | Tool
Detexify helps in writing complex LaTeX symbols, similar to Shapecatcher for Unicode. It searches for the correct LaTeX macros based on a drawing of the shape the users wants. It is a better way to search for symbols instead of going through the symbols-a4.pdf manually.
Dataset | Paper Writing | TeX
The IETF provides official BibTeXs to download. They work for RFCs, BCPs, and drafts.
The BibTeXs for BCPs work, but only, if the BCP consists of a single RFC. If the BCP consists of multiple RFCs, the BibTeX will only show the first one.
For drafts, the draft version number, the last two digits, have to be removed from the URL.
Available entries can be found in the RFC Index and the BCP Index.
https://github.com/google-research/arxiv-latex-cleanerTeX | Tool
This tool allows you to easily clean the LaTeX code of your paper to submit to arXiv. For example, it removes comments and optimizes images.
Search through the documentation of TeX and LaTeX packages. It provides each access to the package documentation, examples or readme.