The whiteboard photographer
The architecture diagram is a photo on someone’s phone.
Commit the diagram next to the code.
For engineers · plain files · your own agent
The whiteboard that draws itself, and commits cleanly.
Mumble listens to your design discussion and draws components, calls and trade-offs as you talk. Every arrow cites the sentence behind it. Files are plain JSON; the reasoning runs on your own Claude Code or Codex.
macOS 13+ · whisper.cpp on your Mac · no API key
Web client
API
Lending service
Reminder queue
Nightly reminder job
Postgres
$ git diff --statdiagram.canvas | 6 +++---Diagrams in git
Your design discussion, as a diff.
~/Mumble/2026-09-28-borrow-desk/
capture.json ← the transcript
diagram.canvas ← the map
audio.wav ← never uploaded
- Stable, readable IDs. No UUIDs.
- Deterministic output: same map, same bytes.
- Layout stored apart from meaning.
diagram.canvas +2 −2
- "id": "reminder-queue",
- "label": "Reminder queue",
+ "id": "nightly-reminder-job",
+ "label": "Nightly reminder job",
"source": { "from": "voice", "utterance": "u058" }
How teams use it
- Design history in git logevery map change is a commit with the sentence behind it
- Design changes in PR reviewthe diff shows what the discussion changed
- Blame an arrowjump from any edge to the utterance that created it
- Hand the discussion to your coding agentpoint Claude Code or Codex at the folder
- Edit from the terminal (MCP)read and write the canvas like any other file
Tip: add audio.wav to .gitignore.
Sound familiar?
The “why did we do that?” archaeologist
Nobody remembers why Postgres beat Dynamo.
Every decision box links to the sentence that made it.
The AI-diagram sceptic
The AI diagram tool invented a Kafka cluster.
Nothing unsaid is drawn as fact. Inference is marked.
Four conversations, one canvas.
Components and labelled calls, drawn with the same ten symbols every time. Switch the style in one click.
See the architecture shape →Web client
Load balancer
API
Lending service
Email provider
Session cache
Postgres
Nightly reminder job
The options on the table, the trade-offs people named, and the outcome only once someone says it.
See the decision shape →QuestionPostgres or DynamoDB for loans?
Option APostgres
Trade-offJoins for availability checks
Option BDynamoDB
Trade-offScales without tuning
OutcomePostgres: we already run it
What happened and when, what you learned, and the follow-ups that were actually agreed.
See the retro shape →02:10 · DeployReminder job v2 ships
02:14 · AlertError rate spikes on /loans
02:31 · FixRolled back to v1
LessonCanary the nightly job first
Follow-upAdd a dry-run flag
Point your own Claude Code at ~/Mumble over MCP. The canvas is an API.
Read the MCP docs →$ claude "add a read cache between API and Postgres in borrow-desk" 1 tile added · marked as inferenceAPI
Postgres
Read cacheInference
Your mic + Mac audio
Whisper, on your Mac
Mumble engine (MCP)
Your Claude Code / Codex
Mumble never holds an API key.
FAQ
Questions engineers ask.
Which model does it use?
Whichever model your Claude Code or Codex is set to. Mumble doesn’t bring a model of its own for the map; transcription runs locally with whisper.cpp.
What exactly leaves my machine?
The transcript and the canvas, sent through your own Claude Code or Codex account to build the map. Audio never leaves your Mac, and transcription-only mode sends nothing at all.
Will it invent a load balancer I never mentioned?
It’s instructed not to invent infrastructure or draw abandoned options as current. Anything without a spoken source is marked as inference.
Which architecture symbols does it draw?
Ten: client, API, service, function, database, cache, queue, storage, load balancer and external system. Anything else stays an ordinary box.
Can I commit canvases to git?
Yes. Canvas files are deterministic JSON with readable IDs, so renaming a box is a one-line diff and adding one is a single block. Add audio.wav to .gitignore.
Can my coding agent read and edit the canvas?
Yes. Point your own Claude Code at ~/Mumble and it can read and edit canvases from the terminal over MCP. It’s a developer setup today.
Can it export to Mermaid?
Not today. The canvas exports as PNG, PDF or to the clipboard, and the summary and transcript as Markdown. The canvas itself is plain JSON if you want to convert it.
Does it know our service names?
Add them to a vocabulary list, for one workspace or one recording, and transcription gets them right.
Does a bot join the design review?
No. Mumble records your microphone and your Mac’s audio, so it works with Zoom, Meet, Teams or a room with a whiteboard, and nothing joins the call.
Can two engineers edit the same board?
Not yet. Canvases are local files, so share them through git for now. Team mode, coming soon, adds sharing and team collaboration.
What do I need?
A Mac on macOS 13 or later, and Claude Code or Codex installed and signed in. Mumble never asks for or stores an API key.
What does it cost?
Nothing while Mumble is in beta, and local use on your Mac stays free after it. Team mode, a monthly plan for shared boards, is coming soon.