Facebook, Twitter, LinkedIn, Spotify, and Slack have all recently followed in Clubhouse’s footsteps by debuting or revealing plans for their own live audio services. Users of the clones would be able to join live group conversations by voice, but not necessarily video—an idea that has prompted 12 million downloads of Clubhouse's app since it debuted last year.

The tech industry's stampede into audio comes amid Clubhouse's growth, despite the limited availability of its invitation-only service. Well-known users include Tesla CEO Elon Musk, Microsoft co-founder Bill Gates, and Facebook CEO Mark Zuckerberg along with non-techies including Oprah Winfrey, Tom Hanks, and the rapper Drake.

Here are Clubhouse's would-be challengers.

Twitter Spaces

Twitter debuted its Clubhouse-rival, Twitter Spaces, late last year as a test. At first, only iOS device users could use the service, and only a limited number of those could host their own rooms, or “Spaces.” Later, Android users were allowed to listen. But in April, Twitter is expected to even the playing field by giving all users similar access.

Twitter Spaces

Still, there are differences between Spaces and Clubhouse. On Spaces, the number of speakers is limited to 11, and all Spaces are public. Also, the number of people allowed into a Space is unlimited.

In contrast, Clubhouse lets dozens of speakers talk at the same time and gives users a choice between hosting public and private rooms. The number of Clubhouse users in a single room is capped at 8,000.

Facebook's clone

Facebook is reportedly in the early stages of developing its own Clubhouse rival. CEO Mark Zuckerberg hinted as much during a conversation earlier this month on Clubhouse, of course.

The news about Facebook’s work broke just six days after Zuckerberg first appeared on the app in February. The project began after Facebook executives told employees to develop something similar to Clubhouse, according to The New York Times.

Facebook, which has cloned features from other rivals, hasn't released any details about the app. But engineer Alessandro Paluzzi recently tweeted leaked mockups created by Facebook engineers of what the app may look like.

They showed that users would be able to broadcast live, start private rooms, or create a video room with friends—a feature that’s already available on Facebook Messenger. The mockups also show a similar design to Clubhouse's, although Facebook has since said the leaked images may not reflect its finished product.

LinkedIn's professionals speak

LinkedIn believes its Clubhouse rival will be different from those developed by others. Instead of being an app focused on social connection, LinkedIn is betting that its service will host professional-focused conversations.

The company said its audio feature, which is still being built, is a response to users who want more ways to communicate. LinkedIn already gives users the ability to publish posts in text, broadcast live video, and brief videos that disappear after 24 hours.

Spotify's new Locker Room

Spotify said on March 30 that it’s buying Betty Labs, the creator of sports-focused social audio app Locker Room, for an undisclosed amount. It plans to give the service a new name and expand it to offer live broadcasts in other categories like music and cultural programming, as well as hosting discussions with celebrities.

Known for its music streaming service, Spotify has already pushed into podcasting by spending hundreds of millions of dollars to grow its podcast library. But users also want live content, the company said, which drove its decision to buy Betty Labs.

Slack’s virtual hallway meetings

Slack started experimenting with audio last year with a feature that mimicked how workplace teams hold impromptu hallway conversations. Recently on Clubhouse, Slack CEO Stewart Butterfield said that the company was taking a page from Clubhouse’s book.

“I've always believed the ‘good artists copy, great artists steal’ thing,” he said last week. “So we're just building Clubhouse into Slack, essentially.”

The new audio feature would be part of a series of additions to Slack, including letting employees post and archive video.

Discord gets in the game

Gaming chat app Discord introduced Clubhouse-like features on Wednesday that let users host group audio conversations. The service, called Stage Channels, lets users host audio-only rooms versus its typical conversations that are combined with video. The new feature is intended for users to host interviews, reading clubs, or karaoke. Like Clubhouse, Stage Channels lets room moderators control who’s speaking as well as add, remove, or delete speakers.

Telegram updates Voice Chats

Earlier this month, messaging app Telegram updated its existing live talk service, Voice Chats 2.0, with Clubhouse-like features. With the update, users can host public chats for an unlimited number of people. Participants can tap a button to virtually “raise their hand” to alert chat administrators that they’d like to speak—a feature similar to that on Clubhouse.