endpointy.io's answer
The simplicity of creating endpoints. No need for complex schema's and type validations. Just name the resource and copy-paste the data object you want.
Mockoon - Mockoon is the easiest and quickest way to design and run mock REST APIs. No remote deployment, no account required, free and open-source.
London Datastore - Datastore, dashboard and API for London's data
MockAPI - MockAPI lets users mock up APIs, generate custom data, and perform operations on it using RESTful interface.
Commons Marketplace - A marketplace to find and publish open data sets.
Mock API Generator - Generate custom data & API to build apps in less than 30s
SnowyOwl - A user friendly tool to manage your dataset