Comparison page
FetchSandbox as a WireMock Alternative
WireMock is powerful. FetchSandbox is for teams who want to start from the spec and get to something useful quickly, without hand-modeling everything up front.
Where WireMock is strong
WireMock is great when you want fine-grained control and do not mind modeling behavior by hand. Many teams use it successfully for custom mocking and replay flows.
Where FetchSandbox fits better
FetchSandbox fits better if the team wants to start from the OpenAPI spec and get to a usable portal plus sandbox without first writing a bunch of behavior by hand. It is not trying to win on maximum flexibility. It is trying to get a team to something usable much faster.