Architecture diagrams
that never go stale.
One diagram of your software, for platform and engineering teams. Your own AI draws it from your code, and the code never leaves your machine. Your team edits it together, and every service shows its live status.
Thirty days free · no card · built on the C4 model
C4
Three levels, one canvas
Context, containers and components, nested. Expand a box to go a level deeper; collapse it to fold the detail away.
Local
Your AI draws it. Your code stays put.
Claude Code or any MCP client reads the code on your machine and draws the canvas. C4Stage receives the drawing, never the source.
Live
Production status, on the diagram
Give a service its health URL. Its status shows on the box and rolls up through every level above it.
Diff
Every save is a version
Preview or restore any version, and compare any two as a diff drawn on the canvas.
HOW IT STAYS CURRENT
Draw it
Connect the AI you already use and it draws the diagram from your code. Or paste Mermaid, or start from a template.
Wire it
Point each service at its health URL. That's the whole integration.
Keep it
Edit it together, review every change as a diff on the canvas, and present it live from one link.
WHEN THE DIAGRAM HAS TO BE RIGHT
Built for the moments a diagram has to be right.
A new engineer's first week
Drill into the real system and play its real request flows, instead of studying a wiki image from two reorgs ago.
An incident call
The failing service glows on the diagram and the flow it breaks lights up red. Nobody spends twenty minutes on what talks to what.
A design review
Propose the change on the canvas, compare it with today's version as a diff, and discuss it in comments pinned to the nodes it touches.
A walkthrough for leadership
Present the diagram you already maintain. One link, no accounts, and everyone watching follows your cursor.
One canvas, three levels.
The C4 model is built in, not a stencil: systems hold containers, containers hold components, all on one canvas. Expand a box to go a level deeper; collapse it to fold the detail away.
Your AI draws it from your code. The code stays with you.
Connect Claude Code, or any MCP client, with one command. It reads the code on your machine, grounds every node and edge in a file, and draws the canvas. C4Stage receives the drawing, never the source. Each run lands as a labeled version you can review or restore.
claude mcp add --transport http c4stage https://c4stage.com/api/mcp --header "Authorization: Bearer <token>"Create a token in your profile. The starter prompt and the seven tools are in the docs.
Production status, on the diagram.
Give a service its health URL and the diagram doubles as a status page. Healthy stays a small dot; a failing service glows red, and its status rolls up through collapsed containers. Play a flow over it and the broken hop lights up red.
Play the request path. Or read it as columns.
A flow is a named request path over the diagram, played stop by stop. The Sequence view pill in the tool rail draws the same flow as columns, participants across the top and stops down the page. Edit it there and the diagram gains every connection you draw; compare two versions and the changes read in the canvas's own green and red.
Every kind of drawing, kept the same way.
A new canvas asks what to draw. Diagrams and sequences are drawn; a Gantt chart, timeline, pyramid or quadrant is edited from an outline and an inspector, or by dragging on the drawing, its walkthroughs playing like flows. Versions, diffs, comments, tags, co-editing, share links and presentations carry over to every kind.
Every save is a version.
Walk the timeline, preview any version read-only, and restore the one that was right. Compare any two and the difference is drawn on the canvas: green added, red removed, amber changed. Below, the demo's real history: a payments rewire, replayed.
Describe the change. It's drawn.
Type what changed in plain language. The assistant adds the nodes, edges and nesting on the canvas while you watch, then hands it back as a draft you can save or discard.
Import
Paste Mermaid, a flowchart or a C4 diagram, and it is rebuilt on the canvas with its boundaries and labels.
Export
PNG for the deck, SVG for the doc, PDF for the review: the whole diagram, or just the flow that is playing.
Mermaid
Copy the whole model, structure and flows, as Mermaid source for the repository. It round-trips: what it writes, it can read back.
Edit together, in real time.
Presence, cursors and a shared draft that merges as everyone types. Comments pin to the node they are about, and unread dots roll up through collapsed containers.
Present it live from one link.
Press Present and share the link: no accounts, no screen-share blur. Every viewer's canvas mirrors yours, the node you select and the flow you play. End the session and the link stops working.
Tags and filters, on every box.
Each node holds its technology, a description, links and tags. Hide a tag and the canvas dims to the slice you care about, such as the PCI surface. Filters ride the URL, so a slice is a link you can send.
ALSO IN THE BOX
Share links
A read-only canvas behind an unguessable link, no account needed. The live demo you just explored is one.
Exports
PNG for the deck, Mermaid for the repository: structure and flows both, one click each.
Command palette
⌘K from anywhere: jump to a node, a canvas or a flow without touching the mouse.
Documents
A Gantt chart, timeline, pyramid or quadrant on a canvas of its own. One counts as a canvas on your plan.
The sequence view
Any flow, drawn as columns instead of a diagram. The view rides the URL, so a link opens on the drawing you were reading.
HOW IT COMPARES
How it compares.
| C4Stage | Competitor A | Competitor B | |
|---|---|---|---|
| C4 model with drill-down | Built in: context, containers and components on one canvas | Native | Shapes, not a model |
| Live production health on the diagram | Health URLs polled live, status rolled up | — | — |
| Request flows | Animated, played over live status | Step-through flows | — |
| AI | Assistant draws on the canvas; your own AI draws from code over MCP | Writes descriptions | Generates static diagrams |
| Real-time co-editing | ✓ | ✓ | ✓ |
| Change review | Diff drawn on the canvas, any two versions | Version history | Revision history |
| Price | 30-day free trial · Pro $14.99 a month | Per editor | Per user |
Compared from the two tools' public product pages, September 2026. Names withheld; C4Stage is not affiliated with either.
PRICING
Simple pricing. Thirty days free.
No card to start. Pick a plan when the diagram outgrows the trial. The subscription belongs to the person who owns the canvases, and the people they invite are included.
Free
Thirty days to draw one system.
$030-day trial · no card
- 1 workspace, 1 canvas, 2 flows
- 3 collaborators per canvas, you included
- 2 live presentation viewers
- 20 AI actions a month
- Read-only after the trial until you pick a plan
Pro
For the person who keeps the diagram for a team.
$14.99a month · or $150 a year
- 3 workspaces, 10 canvases, 10 flows each
- 10 collaborators per canvas
- 25 live presentation viewers
- 300 AI actions a month
Studio
For an organization with more than one diagram.
$29.99a month · or $300 a year
- Unlimited workspaces, canvases and flows
- Unlimited collaborators and viewers
- Unlimited AI actions, within fair use
- Priority support
Enterprise
White label, custom builds, your own infrastructure.
Custom
- White-label deployment
- Custom builds and integrations
- SSO and per-role access control
- A named contact
Every account starts on the thirty-day trial. Limits gate growth, never what you already have. Compare plans → · Questions people ask first →
Draw your system once. Keep it right.
Thirty days free, no card. Connect the AI you already use, or start from a template, and have a diagram your team can trust.