The C4 model, without the DSL.

Structurizr proved that C4 works best as a model. Keystone keeps the model and swaps the text file for a visual editor, so the people who know the system can fix it themselves.

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The C4 model has four zoom levels: context, container, component and code.

Where we agree

Structurizr and Keystone share the big idea: model once, draw many views. Each element exists once, and every diagram that shows it stays in sync. Both can run on your own servers.

The difference is who can hold the pen.

workspace {
  model {
    customer = person "Customer"
    store = softwareSystem "Online store" {
      api = container "API"
      db  = container "Orders DB"
    }
    api -> db "Reads and writes"
  }
}

Why a visual editor matters

A model is only as good as the people keeping it up to date. When updating it means editing a text file and opening a pull request, most of the company just doesn't. The product manager who spots a wrong arrow and the SRE who knows a queue was replaced both end up posting in chat instead.

In Keystone they click the object and fix it, or flag it as an inaccuracy right there.

Keystone object panel for Postgres showing its type, parent and status — Click an object, edit it. No pull request.

Where we differ

Keystone compared with Structurizr
	Keystone	Structurizr
How you edit	Visual editor in the browser	Write DSL, then render
Who can contribute	Anyone with a login	Mostly engineers comfortable with the DSL and git
Reviewing changes	Drafts with a change list, merge and conflict checks	Pull requests on the DSL file
Request walkthroughs	Flows with playback and alternate paths	Dynamic diagrams
Comments and decisions	Comments pinned to objects; decision records with status and approval lock	ADRs as documentation files
Traffic simulation	Built in	Not offered
Model lives in git	Via YAML/JSON import, JSON export and the API	Natively

Based on Structurizr's public docs as of September 2026. Spot something out of date? Email support@keystone-app.io.

Which should you pick?

Structurizr, if…

only engineers maintain your architecture docs, and they want them as code next to the source;
git history is how you want to review every change.

Keystone, if…

architects, managers, SREs and new hires should all be able to read, comment on and fix the map;
you want flows, drafts and decision records in one place;
you want to test designs with simulation. Automation still works through the REST API, YAML and JSON import, and signed webhooks.