Most architecture diagrams are drawn twice. Once on a call, badly, in whatever tool was already open. Then again a week later by whoever has the patience to align boxes, because the first one was unreadable by Thursday.

The second drawing is the expensive one, and it is the one that never happens.

Describe it, and it draws

Type a description of your system and Planner.day draws it on the board. The demo above is the real flow, and it is worth being precise about what happens in the middle, because that is where most “AI diagram” features quietly disappoint.

The model is not asked for a picture, and it is not asked for coordinates. It is asked for Mermaid: a short text definition of nodes and the arrows between them.

That choice decides everything downstream. A definition can be read, checked and repaired if it comes back malformed. A pile of x and y values cannot be checked by anything except your eyes, after it is already on the canvas. And Mermaid is the one format that converts into real bound elements rather than a flat image.

So what lands on your board is boxes and arrows you can edit. Drag one, retype a label, delete an arrow, extend the diagram by hand. It is a starting point, not an artefact you have to accept or throw away.

You can paste up to eight thousand characters, which is deliberate: turning an existing architecture document into a diagram is the use that matters most, and an architecture document is not one sentence.

The icons are matched, not guessed

A box labelled “Lambda function” is a worse diagram than one showing the Lambda mark. So after the definition comes back, the labels are matched against the shape library and the real service icons are swapped in.

The rule underneath that matching is precision over recall, and it is the part worth explaining.

A wrong logo is far more damaging than no logo. An S3 icon on a box labelled “Storage service” is a confident, specific claim about your architecture that happens to be false, and it will survive into a document somebody builds a decision on. A plain box is merely plain.

So the matcher works from a hand-curated table of the words people actually write. Nobody types “Amazon Simple Storage Service”; they type S3. And only genuinely unambiguous terms are in that table, which is why there is no entry for “storage”, none for “database”, none for “queue” and none for “cache”. Those words describe a role, not a product, and guessing which product was meant is exactly the failure mode being avoided.

1,285 shapes

The library that matching draws from is the same one you can browse and drag from by hand:

Pack	Shapes
Azure	636
AWS	296
Product and service logos	233
Agentic and AI tooling	81
Kubernetes	39
Total	1,285

These are the official marks, not approximations, so a diagram you put in front of a client or an auditor looks like the systems it describes.

Alongside them is the ordinary drawing vocabulary you would expect: rectangles, ellipses, diamonds, arrows and connectors that stay attached when you move what they join, freehand drawing, text, images, colours, layering and grouping.

Everyone on one canvas

Boards are collaborative in real time, with a visible cursor per person. No locking, no save button, no merge step afterwards. That sounds like a detail until you watch a team use a whiteboard during a call rather than after one, which is the only time a whiteboard is genuinely useful.

A board can also be published as a public link, so you can show an architecture sketch to a contractor or a client without provisioning them a seat. The link can be revoked.

Where they live

The argument for whiteboards inside a work tool is not that the canvas is better than a dedicated one. It is that the diagram explaining a project sits with the project.

A whiteboard in a separate subscription is one version behind within a month, because keeping it current is nobody’s job. A board in the same workspace as the tasks is opened by the same people, in the same place, for the same reason.

Getting to them

Whiteboards and public sharing are on every plan, including Free. The diagramming shape packs come in from Basic, and the cloud architecture packs from Pro.

You can start free and draw something in about a minute, or read the whiteboards overview for the shorter version.