J and K are vim's keybindings for up and down, which I figured would fit well with the community and users.

What are possible alternative mappings to make it more intuitive to non-developers?

> What are possible alternative mappings to make it more intuitive to non-developers?

Arrows.

But for the other camp - the Emacs people - n and p would be best :).

May I suggest adding an options page to configure the keybindings (and store them in browser.storage.sync)? Happy to send a PR.

Sure, let's discuss this on a GitHub issue first :)

Will fork for w,a,s,d support :P

J and K are intuitive for anyone familiar with vim's keybindings for up and down.

This is also the same layout for Gmail (and many other apps I'm sure)

It's probably set up like that to mirror vim bindings, after all, "J" does look __sort of__ like a down arrow.

I always remember it as “jump” and “climb”. Climb doesn’t start with k, but fair enough.

When I learned HJKL, I used the following mnemonic: The J key (like the F key) has a little bump at the bottom to indicate the resting position for the index fingers in 10-finger writing. Since the bump is at the lower edge of the J key, that means that J goes down.

j/k for down/up most likely comes from Vim.