Topic for specification links, Blend4Web support information and discussions about these APIs.

WebGL 1 Specification
WebGL Reference Card
WebGL Extension Registry

Note: WebGL spec is based on OpenGL ES spec and thus contains mostly links and differences between the two.

OpenGL ES 2 Specification

OpenGL ES Shading Language (GLSL ES)
GLSL ES 1 Specification

NextGen WebGL 2

WebGL 2 Specification
OpenGL ES 3 Specification
GLSL ES 3 Specification