Trello, the office app, has stopped working amid technical problems.
The app is widely used as a way of keeping track of projects, allowing people within a company to see where any given task is.
As with other online tools, it has become especially useful as users are stuck at home in lockdowns, and attempting to co-ordinate their work without being in their office.
Users found that the app was either slow to load or would not load at all.
Instead, they were shown error messages that indicated that there was something wrong with their connection.
"Trello is currently slow or unavailable," an update on Trello's status page read.
"Our engineering team is actively investigating this incident and working to bring Trello back up as quickly as possible.
"Users affected by this incident may notice that Trello is slow or completely unavailable in both the web and mobile apps."
Issues began at around 3.15pm UK time, according to the same page.
Tracking website Down Detector saw a huge surge in issues reported at the same time.
Problems were reported across the world, according to the site. They were particularly concentrated in the US and UK, though that might simply be a consequence of timezones and where the app's users are based.
Trello, which is owned by business software company Atlassian, said late last year that it has more than 50 million users.
