Author: Bob Boelhouwer (INL)
AlchemyAPI (http://www.alchemyapi.com/) provides an online service for keyword extraction, but also for sentiment extraction, text categorization, etc. That means that all tools are available as web services. There is no need to install software locally. This can be considered an advantage. But a disadvantage is that it is not possible to tweak and tune software for special purposes. Moreover, there is only a fixed number of language modules available for the services.For keyword extraction these are: English, French, German, Italian, Portuguese, Russian Spanish and Swedish. It is not possible to use language models for other languages or for special text types.
AlchemyAPI is a commercial product. A license key is required to use it. Luckily, it is possible to receive a free license (http://www.alchemyapi.com/api/register.html), as long as there are less than 1000 transactions per day.