Create SDK from existing software

I am looking to develop? a language translator SDK, that I can use on my server to run many instances, or translations at the same time.? I am looking for only 1 to start...you choose(english and french, english and spanish)? If this project is successful, we will implement a number of other languages.? There is a lot of free software, as well as personal software that does this.? i am looking to basically turn one of these programs into an SDK that i can use, procesing many instances of the same application. Quality and speed are the largest issues.? In terms of quality, it must be comparable to an off the shelf program wiht a dictionanry of 800,000 words and phrases.? Please let me know any thoughts or concerns you may have about this project.