RxNLP is a Text Mining and Natural Language Processing service. One of RxNLP's API's, is the Text Similarity API. It is used for analyzing and computing surface similarities between texts, both long and short. Having the tools to identify text similarity can help with things such as query reformulation, finding and analyzing similar topics, and grouping similar items.
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.