Swoogle: A Search Engine for Semantic Web

Nipun Thennakoon
2 min readDec 29, 2020


SENG 42273 — Semantic Web and Ontological Engineering

Search Engine

We use search engines all the time in our day to day life. Some people use them to search for stuff while others use them to check their internet connection. 😅

A Search engine is basically a software system that systematically searches the world wide web for specific information according to a query specified by a user. To do this, a search engine needs to keep organized records about the websites on the internet. Search engines programs called web crawlers to crawl through web pages on the internet to collect information about them and keep those neatly organized through a process called indexing. When a user searches for something, the search engine looks through their index for relevant content, orders it by relevance (ranking), and finally present the results back to the user.

Search engine process

Semantic Web

The Semantic Web is an extension of the World Wide Web with the goal of making the internet machine-readable. When metadata is included along with the data as semantics, machines are able to make meaningful interpretations similar to the way humans process information to achieve their goals. These semantics are encoded with the data using technologies like Resource Definition Framework(RDF) and Web Ontology Language(OWL).

Current Web vs Semantic Web


So what all this have got to do with Swoogle? Well, you can think of Swoogle as the Google of the Semantic Web. It was a search engine that discovered, analyzed, and indexed knowledge encoded in semantic web documents published on the Web.

Swoogle employed a set of web crawlers to discover RDF documents and HTML documents with embedded RDF content. Then it reasoned about these documents and their individual parts and indexed and recorded meaningful metadata about them in its database. It had a PageRank algorithm which is inspired by Google’s PageRank algorithm, but adapted to the semantics and use patterns found in semantic web documents. Users could access Swoogle using the browser interface or the REST API at the following URLs.

However, it has been discontinued since May 1, 2010, and is not accessible anymore.

So, that's it about Swoogle! Thank you for reading and I’ll see you on the next one. Cheers!