DownDetector shows the largest issues is connecting to Slack, followed by sending messages. Major cities in the US, like New York, Chicago and Boston, were shown in red on DownDetector's map. Slack added 12,000 net paid customers, according to the company’s latest earnings report, up 140 percent from the same period last year. Revenue swelled by 39 percent to $234.5 million.

Status Slack

• Slack is down for many users, with issues loading channels and sending messages on the workplace chat platform.
• A representative told Business Insider that Slack was aware of the issues and working to resolve them.
• Visit Business Insider's homepage for more stories.

Slack appears to be down for many users on Monday as the first workday of 2021 gets off to a rocky start.

Downdetector at one point showed over 15,000 reports of issues.

Slack tweeted on Monday morning that customers may have trouble loading channels and connecting to the messaging platform.

In a later tweet, the company said it had 'updated the severity' on its status website, which reflected a more widespread outage than it previously did.

—Slack Status (@SlackStatus) January 4, 2021

In a statement to Business Insider, a Slack representative said: 'Our teams are aware and are investigating the issue. We know how important it is for people to stay connected and we are working hard to get everyone running as normal. For the latest updates please keep an eye on @slackstatus and status.slack.com.'

Slack has seen a surge in business during the pandemic, as have other companies that offer tools to improve remote-work capabilities, like the videoconferencing company Zoom. Scores of people working from home rely on Slack's messaging software to coordinate with colleagues.

Slack Outage

Slack isn't the only heavily relied-upon service to go down for users during the pandemic. In mid-December, users of Google's Gmail reported lags, error messages, and 'unexpected behavior.' The hiccup came one day after Google experienced a separate, large outage that also affected Gmail, as well as YouTube and Google Maps.

Read more:Salesforce's $27.7 billion acquisition of Slack makes perfect sense, but Marc Benioff's grand vision is going to have to survive a reality check

Down Detector Slack

Salesforce announced in early December that it was buying Slack for $27.7 billion, marking Salesforce's largest acquisition in its history. The deal could bolster Salesforce to compete with Microsoft, which has seen a surge in use of its Microsoft Teams app during the pandemic.