Twitter is “bigger than it’s ever been and it’s growing,” said co-founder Evan Williams, pushing back on what he said was a misperception about the company, while acknowledging it faced “business challenges.”

Speaking in an on-stage interview at The Information’s San Francisco Subscriber Summit on Friday, Mr. Williams also said he got “bored with the content” on Snapchat, although he thought the design of the app was “super cool.” But “it doesn’t maintain my interest—either stories or Discover.”