Evernote has been hit by a cyber attack on Tuesday.
The company said that it’s working to neutralize a denial of service attack.
“We are working to resolve the issue. Updates to follow. Thanks for your patience,” it said via Twitter.
“You may experience problems accessing your Evernote while we resolve this,” it added later.
Denial of service attacks are caused by hacking, sometimes through the hackers hijacking computers to direct huge amounts of traffic to one or several sources.
Evernote was hit by a big attack last year, and hackers obtained some usernames, email addressed, and encrypted passwords.
But spokeswoman Ronda Scott told the BBC that this attack is more limited.
“We do not have an identity to tie to the attack,” she said.
“We’re actively working to mitigate the attack and service is now intermittent.”