&quot;I&#x27;m not sure why you&#x27;d bother over an existing solution like protocol buffers.&quot;<p>For context, protocol buffers did not exist when GSL was devised in 1995 (3 years before google was founded).  So in fact GSL _was_ the existing solution when google came up with protocol buffers.<p>Given GSL is still going strong 21 years after inception is a pretty solid testament to its utility.