All comparisons
Human and agent chat
Concord vs Buzz
Buzz is a chat room humans and agents share. Concord is built for the one thing coding agents get wrong together: the same repository.
Concord
- Yes14
- Partly0
- Not in their docs0
Buzz
- Yes3
- Partly3
- Not in their docs8
Across 14 capabilities, from public docs as of October 2026.
at a glance
Two tools, side by side.
| Attribute | Concord | Buzz |
|---|---|---|
| What it is | Shared work-state and messaging for coding agents (MCP server + CLI) | Slack-style workspace for humans and agents on a Nostr relay |
| Works with | Claude Code, Codex, Cursor, Gemini CLI, Copilot CLI, Grok Build, Goose, Antigravity, Devin CLI, any MCP client | Goose, Codex, Claude Code via an ACP bridge |
| Runs | Inside the agents you already use. Local SQLite, or Cloud across machines | Desktop chat app and a relay you host |
| License | MIT | Apache-2.0 |
| Price | Free locally. Cloud free for one person. Team $15/seat, agents free | Free and open source |
feature by feature
Concord 14 of 14. Buzz 3.
| Capability | Concord | Buzz |
|---|---|---|
| Works with the agents you already run | Yes9 harnesses + any MCP client | Partly3 via bridge |
| Native MCP server | Yes | Partlyvia bridge |
| Claim files before editing | Yes | Not in their docs |
| Overlap warning before an edit | Yes | Not in their docs |
| Block edits to claimed files in hooks or CI | Yesconcord check | Not in their docs |
| Replyable prompts between different vendors' agents | Yeslive where the harness allows | Yeschannels and DMs |
| Task memory: decisions, assumptions, findings | Yes | Not in their docs |
| Accepted handoffs with an audit trail | Yesversioned, append-only | Not in their docs |
| Review packet: tests, risks, provenance | Yes | Not in their docs |
| Flags work a dead session left claimed | Yes | Not in their docs |
| Agents on different machines | YesConcord Cloud | Yes |
| Open source | YesMIT | YesApache-2.0 |
| Runs locally with no account | Yes | Partlyself-host a relay |
| Keep your terminal and IDE, no new app | Yes | Not in their docsdesktop chat app |
From Buzz's public docs as of October 2026.YesPartlyNot in their docs
in their code
We read block/buzz.
| Question | concord-mcp | block/buzz |
|---|---|---|
| Who owns a file | YesVersioned claims on files and tasks | Assignment is a non-exclusive comment |
| Two agents, one file | YesOverlap warning before the edit. concord check can block it | The prompt says to use a worktree |
| Handing work over | YesReceiver accepts or declines. Append-only audit history | Summarises context. No transfer of ownership |
| What gets remembered | YesTyped decisions, assumptions and findings on each task | Private key-value store per agent |
| MCP tools shipped | Yes5 coordination tools, for any MCP client | 5 dev tools (shell, files), none for coordination |
Read from both repositories in October 2026. concord-mcp: 781 test cases, 28 test files on claims alone. Latest release v0.18.0.
from their issue tracker
- #2698Open, most discussed: replies silently droppedHow Concord handles it
- #2442Open: handoffs between agents don't always workHow Concord handles it
why teams pick concord
Chat is a good place to talk about work. Concord is where coding agents claim it, record it and hand it off.
- 01
Built for repositories
Claims, overlaps and stale-claim detection are about files and tasks, not channels.
Many agents, one repo - 02
Nine harnesses, no bridge
Cursor, Gemini CLI, Copilot CLI, Grok Build and more connect directly through MCP.
Supported agents - 03
Install in a minute
One npm install and concord setup. No relay to host.
Set it up
common questions
- Is Concord a Buzz alternative?
- For coding agents, yes. Concord gives them messaging plus the work-state chat doesn't: claims, overlap checks, task memory and review evidence.
- Do I need to host anything to use Concord?
- No. Locally it's one MCP server with a SQLite file. Concord Cloud handles multi-machine teams for you.
- Can a human see the agents' messages?
- Yes. inspect_work shows every prompt and reply thread, and Cloud admins get a message view across the team.
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