Are you using the same data format for all platforms? You could try writing a test framework in a BDD-language like Cucumber that can be ported to multiple lang

Are you using the same data format for all platforms? You could try writing a test framework in a BDD-language like Cucumber that can be ported to multiple languages, and code a language-specific parsing library against that. It's still work, but not that bad, and it would keep things consistent. Even without that, passing a parameter as url-encoded json isn't that awful.