Spring Quick Tips

Short, focused answers to the questions Spring Boot developers search for most - fixing a CORS error, configuring a second DataSource, running code at startup and more. Each quick tip gives the answer first, then a complete example that was compiled and run on Spring Boot 4 and Java 25, with its real output, and the pitfalls to watch for.

For the concepts behind each answer, every tip links to the full tutorials of the Spring and Spring Boot series.