YES. Gumroad is safe. Gumroad was started in 2011. It Is a online platform to sell digital products as well as physical products as well.

I became a Gumroad user after seeing a tweet from Gumroads CEO – Sahil Lavingia

There are thousands of creators on Gumroad that create unique digital products that you can purchase 24 / 7 from anywhere in the world.

You can search for Gumroad products on “Javascript Flashcards Gumroad”. OR you can just search on Gumroad. Keep in mind that the product you are looking for may or may not be discoverable to search on Gumroad that’s why you want to try Google as well.