Buzz is an open source alternative to Slack. Open source Slack alternative from Block: team chat with AI agents as first-class members, built on Nostr. Apache-2.0. 3 days old, still rough at the edges. Apache-2.0 licensed, 26.3k GitHub stars, hosted version available, no terminal required to start, and last released 2026-08-10.
Open source Slack alternative from Block: team chat with AI agents as first-class members, built on Nostr. Apache-2.0. 3 days old, still rough at the edges.
Teams already living in AI coding agents who want those agents as first-class chat participants (their own identity, channel memberships, and audit trail) sitting alongside humans in channels, threads, and DMs, with a choice of Block's hosted buzz.xyz or self-hosting the Rust relay on your own infrastructure. Built by Block, Inc. (Jack Dorsey's company; makers of Square, Cash App), publicly launched 2026-07-21.
You need a settled, battle-tested Slack replacement today. Buzz publicly launched 2026-07-21, three days before this review. Its own README capability table lists mobile clients, workflow approval gates, huddle lifecycle events, and push notifications as not yet shipped, and self-hosted deployments are hitting real first-week bugs. No independent we-migrated-our-team story exists yet for this product.
There is no one-command Docker quickstart. The README's self-host 'Quick start' requires Docker plus the Hermit toolchain (or Rust 1.88+, Node 24+, pnpm 10+, and just) to build and run the relay from source via `just setup && just build`, not a standalone `docker compose up`. Also: the single usage quote found in this review that reads like real product love comes from a Block engineer, not an independent adopter, so treat current social proof as thin and internal.
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Community proof
Some quotes here endorse the approach rather than report first-hand use, or report a problem. We label those.
"The channel as memory has been a big help on larger features that span multiple engineers and many agent sessions. Someplace ad-hoc that's shared makes a real difference."
"I haven't player with Buzz yet but signed up and admire them for thinking differently."
"Am I the only one seeing crazy levels of CPU usage when opening the project's homepage (https://buzz.xyz)? Like "maxing-out-8-cores"-crazy?"
"On a self-hosted relay, managed agents start, connect, and report online, but never respond to mentions or DMs. Affects both the Goose and Claude Code harnesses identically. The Harness Log stays empty, so the failure is invisible from the UI."
"During first-run onboarding, selecting Create a community opens Builderlab authentication in the browser. The authentication endpoint fails before any signup UI loads: login.builderlab.xyz -> ERR_SSL_PROTOCOL_ERROR"
