It's intermittent -- some reporting problems on desktops, and others on mobile devices.
Some issues are with logging in, while others are with getting the feed to refresh.
Downdetector says problems started around 4 p.m. and that 76% of the outages are being reported from the desktop site. Tweetdeck appears to be unaffected by the outage.
Twitter, which has its headquarters in San Francisco, has lost a large portion of staff to layoffs, terminations and resignations in the two months since Elon Musk took over.