qr.cx provides a basic API which can be used to harness qr.cx's URL shortening service for other applications. This works by accessing a particular URL on the qr.cx site which accepts the long URL you would like shortened as a parameter. The shortened URL (or various error conditions) will then be returned in the HTTP response.
The following is a list of SDKs from our SDK directory that matched your search term. Though your definition of an SDK may differ, in our world, we define SDKs as platform- specific tools for consuming existing APIs of the sort we list in our API directory. For example, the Ruby SDK for consuming the Twitter Ads API. If you think an SDK, API, or other asset is missing from our directory, be sure to check our guidelines for making contributions to ProgrammableWeb.