In practice, what I've seen is GraphQL used where REST[0] would have been. I've not seen it used in any case where the solution wouldn't, previously, have been

In practice, what I've seen is GraphQL used where REST[0] would have been. I've not seen it used in any case where the solution wouldn't, previously, have been REST, or in a case for which there would otherwise have been no solution. They are, de facto, competing tech, from what I've seen. I expect there are some examples where that's not true, but I think as experienced by most people it's an alternative to REST. [0] The colloquial sense of REST, that is, which is RESTish. Yes, I know, no-one actually does REST, for practically any value of "actually".