A sandbox helps developers test software in a virtual environment. An API sandbox allows a developer to play with and learn about an API by submitting requests and receiving fake responses that mimic production conditions. A sandbox may also mimic operational behaviors, like error responses, rate limits, and security constraints. Since API sandboxes are virtual endpoints, providers typically do not bill developers for their usage. This makes sandboxes very helpful for use in testing and setting up API integrations within an application. Sandboxes could also help prospective developer consumers test an API before committing to a paid plan. For these many reasons, many popular API products offer a sandbox environment.