450+ free tutorials · Updated for Java 21

Master Java from Basics to System Design

Explore step-by-step tutorials on Core Java, DSA, Spring Boot, Microservices, Kafka, and System Design, featuring tested code examples, real outputs, and interview questions to boost your practical skills and interview confidence.

Start with Core Java Browse All Courses

Main.java

record Course(String name, int lessons) { }

public class Main {
  public static void main(String[] args) {
    var path = List.of(
      new Course("Core Java", 138),
      new Course("DSA", 73),
      new Course("Spring Boot", 32));

    for (var c : path)
      System.out.println("Learning " + c.name());
  }
}

OutputLearning Core Java
Learning DSA
Learning Spring Boot

Step-by-Step LessonsConcepts explained simply
Runnable CodeExamples with real output
Interview PrepFAQs and comparisons
Clear RoadmapKnow what to learn next

Courses

Explore Our Courses

Structured learning paths that take you from your first Java program to designing distributed systems.

Core Java

Syntax, OOP, exceptions, strings, collections and multithreading, with runnable examples and FAQs.

Beginner 138 tutorials

Start course

DSA with Java

Arrays, linked lists, stacks, queues, trees, graphs, sorting and searching, implemented in Java.

Intermediate 73 tutorials

Start course

Design Patterns

Creational, structural and behavioural patterns with real-world Java implementations.

Intermediate 20 tutorials

Start course

Spring Boot

Build production-ready REST APIs, data access, security and monitoring with Spring Boot.

Intermediate 32 tutorials

Start course

Microservices

Service decomposition, communication, resilience, API gateways and distributed data patterns.

Advanced 27 tutorials

Start course

System Design

Scalability, load balancing, caching, databases and designing large distributed systems.

Advanced 31 tutorials

Start course

Apache Kafka

Event streaming with producers, consumers, topics, partitions and Kafka in production.

Advanced 31 tutorials

Start course

MySQL

SQL from the ground up: tables, queries, joins, indexes, functions and administration.

Beginner 90+ tutorials

Start course

MongoDB

NoSQL documents and collections, CRUD operations, queries and data modelling.

Beginner 20+ tutorials

Start course

Roadmap

Your Java Developer Roadmap

Not sure where to start? Follow this order: each step builds on the one before it.

Practice

Practise and Prepare for Interviews

Turn knowledge into skill with solved programs, comparisons and quick-reference material.

40 Java Programs

Number checks, series, arithmetic and loops, each with a full solution.

56 Pattern Programs

Star, number and character patterns to master nested loops.

Java Comparisons

HashMap vs Hashtable, ArrayList vs LinkedList and other interview classics.

Complexity Cheat Sheet

Big-O for common data structures and sorting algorithms at a glance.

Why JavaByTechie

Everything You Need to Grow as a Java Developer

Practical, accurate and focused on what matters in real projects and interviews.

Runnable Examples

Every example is compiled and run, and the page shows its real output.

Structured Paths

Tutorials are ordered into learning paths, so you always know what to read next.

Modern Java

Covers Java 8 to 21: lambdas, streams, records, pattern matching and virtual threads.

Interview Ready

Frequently asked questions, comparisons and design topics in every course.

Learn Anywhere

Clean, fast pages with night mode that work on desktop, tablet and phone.

Free Forever

All tutorials are free to read, with no sign-up required.

About the Author

Hi, I'm Sandeep, Creator of JavaByTechie

Senior Java Engineer & Technical Author

I'm a backend engineer with over a decade of experience building large-scale distributed systems using Java, Spring Boot, Kafka and Microservices. I've worked across fintech, e-commerce and SaaS products, and mentored many developers along the way.

I created JavaByTechie to make learning Java simple, practical and interview-focused. Every tutorial comes from real-world experience: no fluff and no outdated examples, just the concepts and code that actually matter.

Java 8 → 21
Spring Boot
Microservices
Kafka
System Design
MySQL
MongoDB

Built for Your Technical Growth

JavaByTechie is dedicated to helping developers grow their technical skills and prepare for interviews with confidence. From your first Java program to designing scalable systems, every tutorial is written to build real understanding, not just memorised answers.

UnderstandClear explanations of core concepts
PractiseHands-on code and solved programs
PrepareInterview questions and comparisons