Java Collections Module Free
Free Core Java module: collections under load — HashMap, ConcurrentHashMap, LRU. No sign-up.
Four production debug labs plus free Java, Spring Boot & AI, and System Design tutorials run in your browser. The tutorials are the same modules paid users study. No account required.
- HikariCP Pool Exhaustion — connection pool leaks after traffic spikes
- RestTemplate Without Timeout — hanging HTTP clients that freeze the API
- Kafka Wrong Partition Key — out-of-order events across partitions
- Exposed Actuator in Production — security audit failures from open endpoints
- Java Concurrency & Multithreading — paid-track tutorial, free
- Java Collections — paid-track tutorial, free
- JVM Memory & GC — paid-track tutorial, free
- Spring Transaction Management — paid-track tutorial, free
- Caching with Spring — paid-track tutorial, free
- Spring AI Foundations — paid-track tutorial, free
- Scaling & Reliability — paid-track tutorial, free
- Distributed Systems — paid-track tutorial, free
- Classic Case Studies — paid-track tutorial, free
Common questions
Do I need an account to try these debug labs?
No. Free labs and tutorials are static pages in your browser — no sign-up and no trial.
Are the free labs time-limited?
No. They stay free for life. Sign in when you want saved progress or the full debug library in Engineering Hub.
Create free account · Free ATS resume score · Platform features