The fast-growing anonymous mobile app Secret said Monday it had raised $25 million in venture capital and would expand as a social network connecting Facebook friends.

A new feature announced by Secret -- which up to now was an anonymous messaging board -- allows users to log in with Facebook and share with friends without revealing their identities.

"Facebook Login has been our top requested feature, for good reason," the Secret team said in a blog post.

"Our community members want more friend content in their stream, beyond simply the contacts from their phone. Facebook Login gives any user the option to (completely anonymously) connect Secret to Facebook and populate your stream with Facebook friends."

The app for Android and Apple devices rolling out this week will allow this new way of connecting with Facebook friends, and the company sought to reassure its users -- "yes it's anonymous, we don't even store your public name."

Another new feature called Collections will allow people to follow a particular topic.

This provides "the very best of Secret -- the conversations about work, love, loss and even food that have traveled far and wide through Secret give you a sense of what people are really feeling."

Similar to Twitter, Secret users can subscribe to any topic "and automatically receive new secrets from that collection" in their stream.

Secret, which is just six months old, is one of a handful of popular mobile apps that allow people to share comments anonymously.

The second round of funding gives the company a market value of $100 million, according to the New York Times.

The funding comes from Index Ventures, Redpoint Ventures, Garry Tan and Alexis Ohanian, SV Angel, Fuel Capital, Ceyuan Ventures, and "several others that shall remain a secret," the blog post said.