Is there any good OGL clones for SRD protected monsters?

Hey guys! New follower here.

I was wondering if there was a slaad-like creature or even a slaad clone for publishing under the OGL.

I want to use the stat block and some bits of of the lore (like it's biology) for a zine, but I don't understand thoroughly the OGL and SRD of WotC, so I don't want to take any chances.

What about the other SRD protected monsters?