"And we're back!" Instagram posted on Twitter. "We resolved the issue that caused today's outage, and apologize for any inconvenience."
At the outage's peak about 24,000 users from the US alone reported the app was down.
Many people who couldn't access the app took to Twitter to share memes about the outage and caused #instagramdown to trend.
Instagram didn't immediately respond to a request for comment on what caused the outage.