White gas, also known as 'Coleman Fuel' or 'camp fuel' is an outstanding degreaser. A little goes a long way in the most challenging jobs. But it is highly flammable and dries out my skin.

Varsol or mineral spirits is a lesser degreaser, but is more benign, and is good enough for most jobs, including yucky chains.

Any bike product labelled as 'green' is invariably expensive and useless.

Water-based degreasers are particularly bad, in that the strong acids eat at alu and steel parts, and you have to use large volumes due to the basic ineffectiveness of the product. And then what do you do with the greasy liquid residue? Dump it down the drain?