Users and todos are fixed sample data.
Posts can be created, changed, and deleted. Each client IP gets its own copy, which goes back to the sample data YAAK_PLAYGROUND_RESET_AFTER_SECS after its first write.
POST /auth/token returns a bearer token for GET /auth/me. POST /auth/session sets a session cookie for GET /auth/session. Any username with the password yaak logs in.
GET / lists every endpoint and GET /openapi.json describes them.

Nothing is written to disk, so a restart resets everything.

cargo run -p yaak-playground   # http://127.0.0.1:9228

Run yaak-playground --help for the limits. Behind a load balancer that sets X-Forwarded-For, set YAAK_PLAYGROUND_TRUST_FORWARDED_FOR=true.

The image is Dockerfile.playground at the repo root.