Notes JSON API

The example the tutorials build from zero: a notes API you can read end to end in one sitting. It is a teaching example, not a production application.

What it demonstrates

• Five files, five responsibilities. src/note.rs holds the data and ports, src/memory.rs a volatile repository, src/service.rs the application boundary, src/routes.rs the only Axum module, and src/main.rs the composition root.
• A real capability in miniature. The same shape the starter scales up — minus the database, so everything is observable in one process.

Read it in steps

The tutorials build this application from an empty directory: define the domain, accept input, add the adapter, then test it.