LibreOffice: A free and powerful office suite, and a successor to OpenOffice.
Office 365: Students and educators at eligible institutions can sign up for Office 365 Education for free, including Word, Excel, PowerPoint, OneNote, and now Microsoft Teams, plus additional classroom tools.
Markdown
Markdown guide: A free and open-source reference guide that explains how to use Markdown, the simple and easy-to-use markup language you can use to format virtually any document.
Marktext: A simple and elegant markdown editor, available for Linux, macOS and Windows.
LaTeX
LaTeX: A high-quality typesetting system; it includes features designed for the production of technical and scientific documentation. LaTeX is the de facto standard for the communication and publication of scientific documents.
Overleaf : An easy to use, online, collaborative LaTeX editor.
Typst
Typst: A new markup-based typesetting system that is powerful and easy to learn, born out of frustration with LaTeX.
Slides
Marp: Create beautiful slide decks using an intuitive Markdown experience.
Beamer: A LaTeX document class for creating presentation slides, with a wide range of templates and a set of features for making slideshow effects.
Conversion
Pandoc: If you need to convert files from one markup format into another, pandoc is your swiss-army knife.
Handwriting
Google Jamboard: A digital interactive whiteboard that can be used for collaboration
Xournal++: An open source tool for annotating PDF files. It supports pen, mouse, and keyboard input.
Translation and spelling
DeepL : A neural machine translation service first developed within Linguee
Grammarly: A cloud-based typing assistant. It reviews spelling, grammar, punctuation, clarity, engagement, and delivery mistakes in English texts, detects plagiarism, and suggests replacements for the identified errors.
LanguageTool: A multilingual spelling, style, and grammar checker that helps correct or paraphrase texts
Spell-checker: Free Online Spell Checker with URL input.
Antidote: Writing assistance software for English and French.
General tips
OpenAcademic : Various resources and templates related to academic writing
TikZit: A GUI editor for graphs and string diagrams whose files can be included directly in papers typeset using LaTeX.
Inkscape: Professional software for creating vector imagery.
Canva: A graphic design platform that is used to create social media graphics and presentations, and includes readymade templates.
Icons
BioIcons: A library of free open source icons for science illustrations in biology and chemistry (mostly).
BioRender: Thousands of pre-made icons and templates from more than 30 fields of life sciences.
PhyloPic: Free silhouette images of animals, plants, and other life forms.
Data visualization
Data to Viz: Leads you to the most appropriate graph for your data. It links to the code to build it and lists common caveats you should avoid.
DataVizProject: A website trying to present all relevant data visualizations, so you can find the right visualization and get inspired how to make them.