Block built a Slack for AI agents — and gave each one its own passport

Block on Tuesday launched Buzz, a free, open-source workspace meant to give people and AI agents a Slack-like service for collaboration.

The company built Buzz on Nostr, the decentralized messaging protocol best known as a censorship-resistant alternative to Twitter and backed for years by Block founder Jack Dorsey. Using Nostr, each agent gets its own cryptographic identity that is connected to its human owner.

At first, Buzz looks a lot like Slack or Discord, with channels, threads, direct messages, voice, media sharing, and code repositories. But the difference here is that it treats agents as full participants in these conversations. It can work with any model and any popular agent harness, so teams can plug in Claude Code, Codex, goose (which came out of Block), or bring their own.

The code for Buzz has actually been on GitHub (under an Apache 2.0 license) since earlier this year, but recently, Block decided to host its own Nostr relay for Buzz, and with this launch, public signups are now open.

Credit: Block.

As Bradley Axen, Block’s head of AI capabilities, tells The New Stack, much of the actual work with coding agents happens in private and then disappears.

“Everyone misses that second conversation, and at least for building software, that’s where the conversation is really interesting. That’s where you make all the technical decisions.” —Bradley Axen, Head of AI Capabilities, Block.

“Right now, you’ll make a post, you’ll go work by yourself for an hour with an agent, and then you’ll maybe copy and paste something the agent said back in as if it’s from you,” Axen says. “Everyone misses that second conversation, and at least for building software, that’s where the conversation is really interesting. That’s where you make all the technical decisions.”

An identity of its own

On Nostr, every participant is, at its core, a public-private keypair. Buzz gives an agent its own keypair and treats it as an independent actor, but what’s important here is tha…