C4 diagram maker (software architecture)
Add the people and systems, drag them into place and connect them with Connect blocks. On the arrow, write what one uses from the other.
How to useThe system architecture in the C4 model
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C4 diagram maker (software architecture): what it is for
Declare the people, your system and the external systems with a name and a description, and connect the elements with what each relationship does. The C4 context diagram appears next to the text, and the same text accepts the container level.
It is a light way to keep the architecture documented next to the code, as text you can version.
How to use
- Declare people and systems.
- Write the relationships between them.
- Download the diagram as PNG or SVG.
When to use it
- Documenting a system architecture.
- Onboarding new team members.
- Technical presentation for a client.
Frequently asked questions
What is the C4 model?
It is a way of drawing software architecture at four zoom levels, created by Simon Brown: context (the system and who uses it), containers (applications and databases), components and code. The first two are the most used in documentation.
How do I write the elements?
Person(id, "Name", "Description") for people, System for your system and System_Ext for outside systems. For the container level, change the first line to C4Container and use Container(id, "Name", "Technology", "Description") and ContainerDb for databases.
How do I connect the elements?
Rel(from, to, "what it does"), with the element ids. You can also give the technology: Rel(web, api, "Fetches the orders", "HTTPS/JSON").
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.