Like anything like this, the answer is: what did the contract say? If the developer delivered what was laid out in the contract, it's not fraud. If the client r

Like anything like this, the answer is: what did the contract say? If the developer delivered what was laid out in the contract, it's not fraud. If the client really need RoR for some reason unknown to the developer, it should have been specified in the contract. Now, it still isn't a good idea to substitute frameworks, but without it being contractually agreed upon, it would be hard to argue fraud.