Libscore, a service that can tell you which JavaScript libraries the top million websites use, is launching publicly today.

Borne out of payments processing startup Stripe’s Open Source Retreat, Libscore periodically crawls those websites to see which JavaScript libraries they use and makes those results publicly searchable.

Stripe announced its first Open Source Retreat and grant last April, during which it hosted a small group of developers at its office in San Francisco so they could work on an open source project. One of those developers, San Francisco-based Julian Shapiro, created Libscore with the help of Backbone developer Thomas Davis and Digital Ocean creative director Jesse Chase.

Libscore helps you find out, for example, that Backbone is used on about 8,000 of the top million sites and Ember appears on only 185 of them, as Stripe points out. It can also help developers keep track of where their open source work is used.

Take a look at the trending libraries Libscore has pulled out.