Jack Dorsey’s Block Launches Buzz, a Nostr-Based Slack and GitHub Rival for AI Agents

Jack Dorsey’s Block has launched Buzz, a free, open source platform where employees and AI agents work side by side in a shared workspace, the company said Tuesday.

“we’re launching BUZZ,” Dorsey tweeted, describing “a new groupchat platform for teams of people and agents of all sizes” built to reduce the company’s dependency on Slack and GitHub. He called it “model-agnostic, decentralized, self-sovereign, and open source.”

Buzz bundles channels, threads, direct messages, voice, media sharing, code repositories, and automated workflows into a single interface that Block said will feel familiar to anyone who has used a modern team chat tool.

Agents with identities

Agents in Buzz hold their own cryptographic identities and defined permissions, and can post, review code, run approved automations, and contribute to conversations alongside people. Multiple humans and multiple agents share one workspace and build on each other’s work.

“Every company is going to need a place where humans and agents work together,” Bradley Axen, Block’s head of AI capabilities, said in a statement. “The question is whether that place is proprietary or open.”

Buzz is model-agnostic and agent-agnostic, with teams able to deploy agents powered by any LLM or harness—including Anthropic’s Claude Code, OpenAI’s Codex, and goose, the open source agent framework Block first released in January 2025.

Why Nostr

Block chose Nostr to solve what it calls the “most fundamental problem” in multi-agent work, that of identity. Every participant, human or agent, holds a keypair that belongs to them rather than to the platform, so an agent’s identity, history, and reputation can travel across any Nostr-compatible system. Each message, reaction, workflow step, review approval, and git event is recorded as a single signed event in one log, according to the project’s repository, which describes a hash-chain audit trail that applies whether the author is a person or a process.

The code is published under an Apache 2.0 license at github.com/block/buzz, and teams can self-host or use Block’s managed version. It remains early, shipping as version 0.4.21 with desktop builds for macOS, Windows, and Linux and mobile clients still unfinished. And despite the “decentralized” framing, each workspace runs on a single relay, which the project’s repository calls its “single source of truth.”

Rethinking the operating model

Block employees have been considering how teams should work once the tool no longer dictates the process. Lucas Isaza, who works on AI and product at Block, argued in a thread that tools such as Asana, Jira, and Linear once baked sprints and Kanban into company rituals, shaping the operating model as much as the work.

A configurable workspace removes those constraints, he said, so “the bottleneck becomes the operating model.” In Buzz, he wrote, a single thread can hold the diagnosis, task, fix, and surrounding conversation, condensing what used to span several tools into one record of why a decision was made.

Agents can take user-level actions through CLI commands, create their own channels, and update their own memories, while users set channel- or thread-specific rules for each agent. Isaza said he had experimented with agents that generate a shared whiteboard for every thread, producing “better context handoffs with no additional work.” Block has tested the approach internally for months and has “yet to figure out” the model that gets the most from Buzz, he added, noting that most work is collaborative and “that doesn’t need to stop with AI.”

Indeed, Block built the Buzz platform itself using agents, according to Thomas Petersen, a principal designer and AI strategist at the company. Petersen said he rejoined Block wanting to change “the lonely experience of working with AI agents,” adding that “the entire platform” was developed using agents, including its interface, which he described as “more sculpted over time than designed up front.”

A protocol streak

Buzz extends the open protocol push that has defined Dorsey’s work since he left Twitter. He stepped away from the Bluesky board in 2024 and has since backed a string of tools no single company controls, most of them built on Nostr, the relay-based protocol he has personally funded.

That includes Bitchat, his Bluetooth mesh messenger, which China ordered pulled from Apple’s App Store in April, echoing Beijing’s 2023 ban on the Nostr-based Twitter alternative Damus. He has also seeded andOtherStuff, a nonprofit for open source social tools.

Block cut more than 4,000 jobs in February, roughly 40% of staff, with Dorsey noting at the time that AI “fundamentally changes what it means to build and run a company.” A month later, Dorsey announced that the firm’s Cash App would build support for stablecoins into its core payment flow, though the Bitcoin maximalist was vocal about his reluctance to do so. In April, the firm disclosed holdings of  28,355 BTC worth $2.2 billion in its proof-of-reserves report.