What is arc42?
arc42, created by Peter Hruschka and Gernot Starke, structures architecture documentation into twelve sections: introduction and goals, constraints, context and scope, solution strategy, building block view, runtime view, deployment view, crosscutting concepts, architecture decisions, quality requirements, risks and technical debt, and glossary. It prescribes no diagram notation, so teams often draw C4 diagrams inside it: the context diagram in section 3, container and component diagrams in the building block view (section 5), and dynamic diagrams in the runtime view (section 6). Its own guidance is to document only what readers need rather than fill in every section.
Also known as: arc42 template.
Related terms
- C4 Model — A lightweight architecture visualization approach that describes software systems across four levels: System Context, Container, Component, and Code.
- Architecture Decision Record (ADR) — A short document capturing a single architecturally significant decision, its context, and its consequences.
- Living Documentation — Documentation that is generated or validated from the running system, so it stays accurate as the system evolves.