As you may have guessed from the title, the following is a list of (almost) 10 tools that make my life easier. You may know most of them, but my list my rules.
LaTeX is a high-quality typesetting system that allows you to produce astonishingly beautiful documents that people with like, at least from an aesthetics perspective.
Overleaf is an online collaborative LaTeX editor that saves you from the burden of installing LaTeX on your machine and assists you in the process of writing.
Markdown is a text-to-HTML conversion tool for web writers. It allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML). Many extensions are available. For example, this web page is generated using GitHub Flavored Markdown.
HackMD is an online collaborative Markdown editor that supports many useful features to write mathematical expressions and generate sequence diagrams, flow charts, music sheets and much more.
Mermaid allows you to generate diagrams and flowcharts from text using a simple markdown-like script language. It is one of the many tools supported by HackMD.
Matcha is an online Mathematics editor that, among other things, allows you to draw complex figures and export them as LaTeX code.
code2flow is an online editor that allows you to draw flowcharts through a simple syntax. No more messy drag and drop editing.
Stack Exchange is a network of question-and-answer websites on topics in diverse fields (e.g., programming, math, cryptography, computer security) with many cool people who are there to help and learn.
Git is a free and open source distributed version control system designed to handle everything from small to very large projects. It is perfect to collaboratively work on the development of a software.
GitHub is a development platform that offers the distributed version control functionality of Git, plus other cool features to develop and share your software.
Python is my favourite programming language. The Zen of Python gives an idea of the reason behind this choice.
Spyder is an integrated development environment for scientific programming in Python. It usually works fine.
Atom is a hackable text editor that you can personalize until it perfectly fits your needs. Oh, it has a lovely ad.
Remix is an online integrated development environment that allows you to write and deploy Solidity smart contracts very easily. If you do not know what is a smart contract, just remember that it is not related to music.