Google has launched a free tool allowing websites and blogs to offer customisable searches to their users.

Site owners signing up for the service can ‘paste’ it into their webpages and select the sites they want included in searches.

In return, they share revenue with Google from text-based ads tied to the service, although government and non-profit groups can use it without ads.

The service seems pretty similar to that already offered by Rollyo, as numerous blogs have pointed out.

However, Google’s VP of search products Marissa Mayer told the FT that the launch would be “the most significant… that Google would announce in the final months of this year.

Mayer also said: “We want to make it easy for anyone to create a search engine about all of their favorite topics, without needing a Ph.D. Everyone can harness the power of Google technology to create a personalised search experience that reflects specific knowledge and interests.”

Here are some examples of sites already on board.