Initially, there were demos that I created by canvas, but now there is more than canvas.
If you are interested in learning how to create, you can find articles in my blog.

threejs

• 3D particle animation, particles with a bloom effect move from different position to their respective destination in order to form a given image, and the final result can resemble the fluid motion of an ocean surface.

canvas or svg

• particle animation. (related blog)

• font particle animation. (related blog)

• a drawing board, you can draw and save a screenshot of your work

• to save a specific part of an image

• to generate images of different size at once

• a round animation diaplays the changes according to percentage. canvas version / svg version

• a path animation made with svg (related blog)

others

• Hiragana helps to practice Japan hiragana and katakana in order to improve familiarity, this would be helpful if you are just started to learn Japan.

• Japan Vocabulary helps in becoming familiar with hiragana at the N4 and N5 levels, the words are sourced from 新版中日交流标准日本语初级.

• Html5 recording is useful to record your computer screen, you can download and review the video which you have recorded. related blog