Jack Dorsey’s Block wants to take on Slack. The twist is that the workforce it is building for is half machine. Its new app, Buzz, is an open-source workspace where humans and AI agents share the same channels, and every agent carries its own portable identity.

Block, the Dorsey-led fintech behind Square and Cash App, has released Buzz, a free, open-source platform for humans and AI agents to work together. Reviewers have framed it as a direct challenge to Slack, one built for the age of agents.

On the surface it looks familiar. Buzz has channels, threads, direct messages, voice, media sharing, code repositories, and automated workflows. Anyone who has used a modern team chat tool will recognise it.

Agents as colleagues, not assistants

The difference sits underneath. In Buzz, AI agents are not bots waiting for a command. Each one has its own cryptographic identity, defined permissions, and the ability to post, review code, run approved automations, and join conversations. Multiple agents and multiple humans share a workspace and build on each other’s work.

“Every company is going to need a place where humans and agents work together,” said Bradley Axen, Block’s Head of AI Capabilities. “The question is whether that place is proprietary or open. We built Buzz because we believe it should be open.”

It is model-agnostic. Teams can plug in agents built on any model or harness, such as Claude Code, Codex, or Block’s own goose. They can bring their own, or build new ones.

The identity bet

Buzz runs on Nostr, the decentralised protocol Dorsey has long backed. Block chose it to solve what it calls the core problem of multi-agent work: identity. Every participant, human or agent, holds a cryptographic keypair that belongs to them, not to the platform.

That means an agent’s identity is not tied to a vendor’s API key. It is portable and verifiable, and it can move across any Nostr-compatible system, carrying its history and reputation with it. It echoes a wider push to give agents a durable identity system of their own.

Open versus locked in

Block’s real argument is about control. Most companies are building their agent infrastructure inside proprietary platforms run by a handful of providers, which breeds fragmentation and vendor dependency. Buzz ships under an Apache-2.0 licence. Teams can run their own instance with full control over data and agents, or use Block’s hosted version.

The open, self-hosted pitch should land with European firms wary of US vendor lock-in and of data leaving their control. It also chimes with the drive to give autonomous agents their own standing as they take on real work.

A crowded room

Buzz is still early. The Git integration is nascent. And Block is entering a field where Slack, Microsoft Teams, and OpenAI all race to deploy agents in the workplace. Whether openness beats the incumbents’ reach is the open question. So is oversight: handing agents their own identities and permissions is convenient, and it is exactly the autonomy that safety researchers keep warning about.