Website Categorization API

The Website Categorization API returns a given domain's category based on our content analysis and machine learning in XML or JSON.


Returns the category of a given domain

How do we categorize websites?
The categorization algorithm is able to accurately classify an unknown website as one of 25 main categories and 219 sub-categories. The ability to algorithmically generate categories for a given list of websites is enormously powerful and can be used for lead generation, marketing segmentation and online filtering. SimilarWeb’s categorization engine uses a multi-class learning algorithm to generate a category for a given website using website content tags, similarity results and a learning set of 2.5M categorized websites. SimilarWeb’s categorization results are constantly improving through machine learning and incorporation of customer input. Category results are rigorously cross validated and tested.

Get the full categories' list here


Website Categorization API endpoint : category

JSON Endpoint Lookup{domain}/v2/category?Format=JSON&UserKey={UserKey}

XML Endpoint Lookup{domain}/v2/category?Format=XML&UserKey={UserKey}


Params Description
Domain Enter your target domain including only the top-level and second-level names, ie: ""
UserKey Enter the user key sent to you by email. You can also find your user key in the API dashboard.

One request to this API is worth 3 hits

Please note that sending one request to the SimilarSites API results in 3 hits being counted against your total number of monthly hits.

Example: Category API input for ""


Example: Category API output in json for ""

 "Category": "Sports/Basketball"


  1. What is the difference between Website (Domain) categorization and URL categorization?

    Website (Domain) categorization will classify the website, telling you what category it belongs to as a whole.
    URL categorization will classify the page itself, telling you what category its content belongs specifically.

  2. Where can I see the full list of existing categories?

    You can find the full list of categories here.

  3. What happens if a website is relevant for more than one category?

    At this point our API will provide the one category that best matches the website.