Calais: Connect. Everything.

We want to make all the world's content more accessible, interoperable and valuable. Some call it Web 2.0, Web 3.0, the Semantic Web or the Giant Global Graph - we call our piece of it Calais.

What Calais does sounds simple – what you do with it could be simply amazing

The Core: The OpenCalais Web Service

The OpenCalais Web Service automatically creates rich semantic metadata for the content you submit – in well under a second. Using natural language processing (NLP), machine learning and other methods, Calais analyzes your document and finds the entities within it. But, Calais goes well beyond classic entity identification and returns the facts and events hidden within your text as well.

The tags are delivered to you; you can then incorporate them into other applications - for search, news aggregation, blogs, catalogs, you name it.

If you're not familiar with OpenCalais, the Document Viewer is a way to get a quick peek at OpenCalais output. Paste a chunk of text into the Document Viewer window, submit it, and see the resulting OpenCalais tags. Note that this is not the OpenCalais web service; it is simply a demonstration of what OpenCalais can do.

You can also visit our Showcase for examples of how developers have implemented OpenCalais in a variety of ways.


The metadata gives you the ability to build maps (or graphs or networks) linking documents to people to companies to places to products to events to geographies to… whatever. You can use those maps to improve site navigation, provide contextual syndication, tag and organize your content, create structured folksonomies, filter and de-duplicate news feeds, or analyze content to see if it contains what you care about. 


The Tools: A Growing Ecosystem of Calais-Enabled Capabilities

The OpenCalais Web Service is a powerful capability - but using it to deliver value to real people requires applications and the tools to build them. Major focus areas of the Calais initiative are delivering the tools with which to build great applications and fostering the community of developers that will make those applications happen.


To learn more about the growing set of OpenCalais tools please take a moment to visit the Showcase and Documentation sections of the site.

The "Open" in Calais

The web service is free for commercial and non-commercial use. We’ve sized the initial release to handle millions of requests per day and will scale it as necessary to support our users.

Having Trouble? Got Questions?

If you've lost or forgotten your API Key, you can retrieve it here.

Visit our Forum to participate in discussions among OpenCalais developers and to get answers to many of your questions.

FAQs also offer insights and answers to many user questions.