The following tools are used for documentation.

Markdown

Markdown Guide is the main documentation language.

If you also want to add diagrams to your documentation have a look at Mermaid

Greenshot

Create Screenshots with Greenshot.

Snagit

We use Snagit on the mac for screenshots and short videos.

Camtasia

We are creating technical videos for demos and training with Camtasia.

Diagrams.net

We use diagrams.net to create diagrams that are compatible with Visio and other formats.