Co-founders of Instagram, a smart phone photo-sharing platform, Kevin Systrom and Mike Krieger have resigned from their positions. The duo resigned from their positions as Chief Executive and Chief Technology Officer respectively.

Systrom and Krieger met at Stanford University and worked separately in Silicon Valley before forming Instagram in 2010. The photo-sharing app has over one billion active monthly users and has grown over the years by adding features such as messaging and short videos.

Recall that Facebook which is owned by Mark Zuckerberg acquired Instagram in April 2012 for a billion dollars.  Later in June, the platform announced it passed a billion active users. It also unveiled a new long-form video feature in a bid to attract ‘creators’ like those on YouTube.

According to several media reports on Tuesday, the departures at Facebook’s fastest-growing revenue generator is coming just months after the exit of Jan Koum, a co-founder of Facebook-owned messaging app, WhatsApp.

These exits leave the social network without the developers behind two of its biggest services. They also come at a time when Facebook’s core platform is under fire for how it safeguards customer data, as it defends against political efforts to spread false information.

Systrom wrote in a blog post on Monday that he and Krieger planned to take time off and explore “our curiosity and creativity again”.

In a statement, Zuckerberg described the two as extraordinary product leaders from whom he had learnt a lot working with.

“I wish them all the best and I’m looking forward to seeing what they build next,” Zuckerberg added.

Zuckerberg ally, Chris Cox, who leads product development for Facebook’s main app, gained oversight of WhatsApp and Instagram, which had been given independence when Facebook bought them.

Instagram had been hailed in Silicon Valley as a flashy acquisition, with the team kept relatively small and Systrom having the freedom to add features such as peer-to-peer messaging, video uploads and advertising.