arc42

All you ever need for your software architecture.

arc42.org

req42

Home of agile business analysis and requirements engineering.

req42.de

systems42

Agentic engineering based on our proven templates req42 and arc42.

systems42.org

systems42 sits on top of the two templates. The blue of arc42 and the green of req42 meet in the systems42 mark, which is why the site uses both colours throughout: green where requirements are meant, blue where architecture is meant, and both where the two come together.