Free Spring Boot debug labs
Free Spring Boot labs for HikariCP pool exhaustion, RestTemplate timeouts, Kafka keys, and exposed Actuator, plus Java and system design modules. No sign-up.
Practice real production incidents in your browser: HikariCP pool exhaustion, RestTemplate hangs, Kafka events out of order, and publicly exposed Actuator. Java, Spring, and system design modules sit on the same hub. No account.
These are not toy quizzes. Each production lab shows the broken Spring code, the symptoms you would see on call, and a diagnosis you submit in the browser. The four lifetime-free labs cover connection leaks, HTTP client timeouts, Kafka partition keys, and Actuator hardening.
Java concurrency, collections, and JVM memory modules, plus Spring transactions, caching, Spring AI, and system design case studies, are open without sign-up. Sign in only when you want saved progress and the rest of the lab library.
What you will cover
- HikariCP connection pool exhaustion after a traffic spike
- RestTemplate with no connect or read timeout
- Kafka producer using a random partition key
- Spring Boot Actuator /env and /heapdump left public
- Free Java, Spring Boot, and system design module previews
Related free labs and modules
Common questions
What is a free Spring Boot debug lab?
A static page with a real production bug: leaked JDBC connections, a hanging HTTP client, a wrong Kafka key, or an open Actuator endpoint. You read the broken code, pick the root cause, and submit a diagnosis in the browser. No account and no trial clock.
Which production bugs can I practice without signing up?
HikariCP pool exhaustion (d11), RestTemplate without timeout (d18), Kafka wrong partition key (d40), and exposed Actuator in production (d25). Those four labs stay free for life.
Do I need an account for the Java and system design modules?
No. The first topics in Java concurrency, collections, JVM memory, Spring transactions, caching, Spring AI, scaling, distributed systems, and case studies open as a guest. Sign in when you want the rest of each module and saved progress.
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