Enterprise-grade Java backend engineering knowledge base covering Core Java, JVM, Spring Boot, databases, distributed systems, microservices, system design, testing, security, performance, and backend interview preparation.
This repository is a long-term engineering knowledge base for becoming a strong pure Java + enterprise Spring Boot backend developer, while also preparing for senior-level backend interviews.
It is designed to feel like a professional engineer's handbook, not a collection of random interview questions:
- Java knowledge base
- Spring Boot handbook
- Backend engineering handbook
- System design notebook
- Interview preparation system
- Project architecture journal
- Revision system
- Daily learning system
Developers targeting roles such as Java Backend Engineer, Spring Boot Developer, Senior Java Developer, Java Microservices Engineer, or Enterprise Application Developer, progressing from junior to staff/architect thinking.
Every note aims to answer:
- How does this work?
- Why is it designed this way?
- When should I use it (and when not)?
- What can go wrong in production?
- How would I explain this in an interview?
Principles: understand before memorizing, prefer simple designs, know the trade-offs, connect theory to production, measure before optimizing, and security by default.
00-Home/ Dashboards, roadmap, weekly review
01-Java/ Core Java, collections, concurrency, JVM
02-Spring/ Spring Core, Boot, MVC, Data/JPA, Security
03-Backend-Engineering/ HTTP, REST, messaging, caching, resilience
04-Database/ SQL, indexes, transactions, scaling
05-System-Design/ Fundamentals, distributed systems, HLD, LLD
06-DSA/ Data structures, algorithms, patterns
07-Interview/ Interview question bank by category
08-Projects/ Project docs and architecture decisions
09-Engineering-Practices/ Clean code, SOLID, testing, CI/CD
10-Daily-Notes/ Daily learning log
90-Templates/ Reusable note templates
99-Archive/ Retired notes
- Java: language, collections, generics, streams, concurrency, JVM internals, GC, memory model
- Spring: IoC/DI, Boot auto-configuration, MVC, Data/JPA, Hibernate, transactions, security, AOP
- Backend: HTTP, REST, API design, auth, caching, Redis, Kafka, resilience, observability
- Database: SQL, indexing, transactions/ACID, isolation levels, replication, sharding
- System design: scalability, CAP/PACELC, distributed systems, HLD and LLD case studies
- DSA: data structures, algorithms, and problem-solving patterns
- Interview prep: category question banks emphasizing depth over trivia
- Engineering practices: clean code, SOLID, testing, code review, CI/CD, production readiness
- Open the folder as an Obsidian vault.
- Start at [[Home]] (
00-Home/Home.md). - Follow the [[Learning-Roadmap]] in the order that suits your level.
- Create new notes from the templates in
90-Templates/. - Link related concepts as you learn so the knowledge graph grows.
This vault relies on Obsidian's built-in features (backlinks, graph view, properties, templates). No community plugins are required. Notes use YAML frontmatter (Obsidian Properties) for metadata and [[wikilink]] style cross-references.
This is primarily a personal engineering knowledge base. When contributing:
- Keep notes technically accurate and concise
- Include practical examples and explain trade-offs
- Link related concepts instead of duplicating content
- Do not include copyrighted material verbatim
- Never include credentials or sensitive information
This repository contains knowledge and examples only. Never commit passwords, API keys, tokens, JWT secrets, cloud credentials, or .env secrets. Use placeholders such as YOUR_API_KEY, YOUR_DATABASE_PASSWORD, YOUR_JWT_SECRET. For the hosted repository, enable Dependabot alerts, secret scanning, push protection, and code scanning where appropriate.
See LICENSE. This repository contains personal learning notes and educational material.