What is ShaderLab?
ShaderLab is the WebGL2 GLSL Editor for the browser. Code your shaders right in your browser with a live view to progress in the background. Then share and garner feedback through comments and check out other creators.
Comments and Reviews
Said about ShaderLab as an alternative
Shaderlab is the only solution that allows using external images from imgur (or any website that allows for cross-domain access) as input textures, and allows the user to use his own MP3 files as audio inputs. It also have a Vim mode by pressing F9 on the editor, to use search and replace with regexp.
You can use custom textures and custom audio with your shaders.