application.properties ↔ application.yml

Notes: list entries use key[0]=value in properties and - value in YAML. A multi-document YAML file split by --- becomes #--- separated blocks in properties, which is what Spring Boot 2.4+ expects. Comments are carried over and attached to the key that follows them. When a file will not parse, click a line number to jump straight to it, or use the repair button beside the message. Anything a repair changes can be undone. Problems that need a real decision — a key used both as a value and as a parent, for instance — are reported without a repair button, because guessing there would be worse than asking.