The social network site Twitter is talking with Salesforce.com, Google, and others over a possible takeover of the company, people briefed on the discussions said Friday. The discussions are in the early stages, these people said, and there is no guarantee that a deal will be reached.

At the same time, Twitter is weighing a possible revamping of the company that could involve divestitures and layoffs. The company is working with the investment banks Goldman Sachs and Allen & Company on its options.

Shares of Twitter, which is based in San Francisco and has 313 million users worldwide, soared 21 percent, closing at $22.62. Twitter and Salesforce declined to comment.

Since its splashy debut on the public markets, Twitter has struggled to grow while battling competition from rivals old and new. Lack of growth has begun to eat away at advertiser demand, which had remained robust even as Twitter’s overall number of users stagnated. Advertisers aiming for big audiences tended to choose Facebook, while those looking for younger audiences have the option of Snapchat.

Twitter has begun a turnaround effort built on video and live streaming video in the hopes users will flock to the service to watch sporting events and news. The company also shifted its focus to selling more premium video ads.

Salesforce has publicly expressed interest in owning a social network, which the company believes can bolster its main business of selling software and service to business clients.

Though Salesforce itself declined to comment on any discussions with Twitter, its chief digital evangelist, Vala Afshar, posted on Twitter some of the attractions that a deal might have for his employer. Among them: Twitter’s “personal learning network,’’ and “the best real-time, context-rich news.’’