Have coupon and keys and want Steam world dig and other games

I have:

Coupon: 25% off Velocity Ultra( steam)

keys:

Dungeon Dashers: Standard Edition(steam)

Tiny Barbarian DX(steam)

Guns of Icarus Online( steam)

Beast Boxing Turbo( steam)

I want:

Steam World dig(steam)

Tiny brains( steam)

Not The Robots( steam)

Pixel Piracy( steam)

Interstellar Marines( steam)

Blade Symphony( steam)

Kingdom rise( steam)

Can someone plays tell me if it is legal to trade indie royal and humble bundle keys on this site?