Online information storage company Evernote has said that hackers have breached its computer network and accessed some usernames, email addresses and passwords.
The firm asked all users to reset their passwords, following the security breach by hackers.
The California-based company, that allows people to store and organise personal data on an external server, is thought to have about 50 million users, the BBC reports.
A statement on the firm's website said its security team discovered and blocked "suspicious activity on [their] network that appears to have been a coordinated attempt to access secure areas of the Evernote service".
According to the report, the firm apologised "for the annoyance" caused by the breach, which it said is becoming "far more common" at other "large services".
Evernote acts like an online personal organiser, with users able to save data such as video clips, images, web pages, notes and itineraries in an external storage system commonly known as the cloud. (ANI)