qm vs Munder Difflin: YC's Multiplayer Harness or a Local-First Agent Office?

qm earned its stars fast — “a multiplayer agent harness for work, in Slack and on the web” is a great pitch, and Y Combinator shipping open-source agent tooling is good for everyone. We get asked about it a lot, so here’s the honest comparison.

The same problem, from opposite ends #

Both tools exist because one CLI agent in one terminal doesn’t scale: you want several agents working in parallel, safely, with scheduled background work and a way to reach them from where you already are.

qm answers it org-first. A headless Node core (installed via npm exec qm init) that your team reaches through Slack and a web UI. Each “employee” gets an isolated workspace; skills are shared with scope-based permissions and can be promoted org-wide; admins set the security posture — Strict (approval-gated), Auto (default screening), or Dangerous — for everyone at once. Background work runs as crons and watches.

Munder Difflin answers it desk-first. A desktop app on your machine where every agent is a real CLI process in a real terminal — Claude Code, Codex, Antigravity, Copilot, Grok, Kimi, and more, riding the subscriptions you already pay for. The floor is visual (yes, it looks like The Office), a GOD orchestrator routes work, agents share long-term memory, and background work runs as scheduled missions with Slack and webhook triggers.

If you map the concepts across, most of qm’s vocabulary has a Munder Difflin counterpart:

Job to be done	qm	Munder Difflin
Safety levels	Strict / Auto / Dangerous postures	Auto-mode toggle, per-agent pause/halt, tool gating, circuit breaker, confirm-word voice safety
Background work	Crons and watches	Scheduled missions + Slack/webhook triggers
Reusable behaviors	Shared skills with scoped permissions	Agent Gallery roles + shareable agent recipes
Reach it from anywhere	Slack + web UI	Slack + Remote Control from your phone
Isolation	Isolated workspaces per employee	Isolated git worktrees per agent
License	MIT	MIT

What each has that the other doesn’t #

qm’s edge is multiplayer. One shared harness, unified identity, org-level admin, skills promotion across scopes. If your team wants a single fleet everyone shares from Slack, that’s qm’s home turf, and Munder Difflin doesn’t try to be that.

Munder Difflin’s edge is everything you can see and touch:

• Real terminals. Every agent is a watchable CLI process — when something goes sideways, you read the actual session, not a log abstraction.
• Voice orchestration. Flip on talk mode and Michael greets you already knowing every agent’s status, steers work, changes settings from an allowlist, and waits for a spoken confirm word before anything destructive.
• A built-in IDE. Monaco (the VS Code engine) one click over the floor: side-by-side diffs of agent changes, clickable commit history, branch compare, guarded checkout, live markdown previews.
• Local-first by construction. No shared server, no code upload — agents, state, and memory live on your machine.
• Auto-update. The app ships its own updates from GitHub releases; you just click “restart to update.”
• A longer release train. Public releases since v0.2.0, now at v0.3.5, with the reliability work battle-tested by a growing contributor community.

Which should you use? #

• Your whole team wants one shared fleet with org-level control → qm. That’s what multiplayer-first buys you.
• You want your own agent office, on your own machine, with everything visible → Munder Difflin. Simpler to adopt (download, open, hire), nothing leaves your computer, and the interfaces — floor, voice, IDE — are things a headless harness structurally can’t offer.
• Honestly? Some teams will run both. qm as the shared org layer, Munder Difflin as the personal floor where you watch and steer your own agents. They don’t compete for the same seat.

Facts about qm above come from its public README as of August 2026 — check the repo for the current state, because both projects move fast.

Try Munder Difflin free — macOS, Windows, Linux, MIT-licensed. And if this comparison helped, a GitHub star helps more people find it.

FAQ

What is qm?

qm (github.com/yc-software/qm) is Y Combinator's open-source 'multiplayer agent harness for work' — a headless Node.js core with a web UI and a Slack plugin. Team members get agent 'employees' with isolated workspaces, shared skills with scope-based permissions, background crons and watches, and three security postures (Strict, Auto, Dangerous). It's MIT-licensed and installs via npm.

What's the main difference between qm and Munder Difflin?

Where the harness lives and what you can see. qm is multiplayer-first: a shared server your whole team reaches through Slack and the browser. Munder Difflin is local-first: a desktop app on your machine where every agent is a real CLI process in a real terminal you can watch, with a visual office floor, voice orchestration, and a built-in IDE. They cover the same core jobs — postures, scheduled work, Slack, skills — from opposite ends.

Does Munder Difflin do what qm's security postures do?

Yes, the same job with different controls: a floor-wide auto-mode toggle (the equivalent of switching between approval-gated and autonomous), per-agent pause/halt, voice-level confirm words for destructive actions, tool gating, a circuit breaker for runaway agents, and spend/scope escalation to a human. qm's Strict/Auto/Dangerous is org-level configuration; Munder Difflin's controls are per-floor and per-agent.

Does qm have voice control, an IDE, or git visualization?

Not as of this writing. qm's interfaces are Slack and a web UI. Munder Difflin ships realtime voice orchestration (a talking Michael with live floor context), a built-in Monaco IDE with commit history, branch compare and side-by-side diffs, markdown previews, real watchable terminals, and auto-update.

Which one should I use?

Use qm if your whole team wants one shared harness in Slack with org-level admin control. Use Munder Difflin if you want your agent office on your own machine — watchable, local-first, with voice and an IDE — riding the CLI subscriptions you already pay for. Both are MIT-licensed; some teams will genuinely want both: qm as the shared org layer, Munder Difflin as the personal floor.

Is Munder Difflin older than qm?

Munder Difflin has been shipping public releases since v0.2.0 in mid-2026 and is on v0.3.5 with a stable auto-updating release train, while qm is a newer project that grew popular quickly. Popularity and maturity are different axes — evaluate both against your workflow.

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