750+ 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
  • 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

21 courses in four tracks, from your first Java program to Spring, distributed systems and databases.

Java

Language, problem solving and design · 5 courses

All Java tutorials
Start here

Core Java

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

  • OOP
  • Collections
  • Exceptions
  • Multithreading
  • Streams
Beginner 138 tutorials
Start course

Java Programs

Solved programs with output: patterns, strings, arrays, numbers and logic.

Beginner180+ programs
LTS

Java LTS Features

What each long-term support release added, from lambdas to virtual threads.

Intermediate5 releases

Data Structures & Algorithms

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

Intermediate73 tutorials

Design Patterns

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

Intermediate20 tutorials

Spring

Build and secure production applications · 5 courses

All Spring tutorials
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Spring Boot

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

  • REST APIs
  • Configuration
  • Data access
  • Testing
  • Monitoring
Intermediate 32 tutorials
Start course

Spring Data Access

JPA, Hibernate, JPQL, transactions, pagination and database migrations.

Intermediate11 tutorials

Spring Security

Authentication, authorization, JWT, OAuth 2 and method-level security.

Advanced7 tutorials

Spring Batch

Jobs, steps and chunks, with skip, retry and restart for large data imports.

AdvancedComplete guide
New

Spring AI

Add AI models to Spring apps: chat clients, prompts and core concepts.

IntermediateGuide

Architecture & Messaging

Design systems that scale · 3 courses

System design tutorials

Microservices

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

Advanced27 tutorials

System Design

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

Advanced31 tutorials

Apache Kafka

Producers, consumers, topics, partitions and running Kafka in production.

Advanced31 tutorials

Databases

SQL and NoSQL, from fundamentals to production · 8 courses

Database tutorial
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Database Fundamentals

What a database is, SQL vs NoSQL, ACID, transactions, isolation levels and locking.

  • SQL vs NoSQL
  • ACID
  • Transactions
  • Isolation
  • Locking
Beginner 9 tutorials
Start course
SQL

MySQL

Tables, queries, joins, indexes, functions and administration.

Beginner90+ tutorials
SQL

Oracle

Architecture, schemas, Oracle SQL, read consistency and PL/SQL basics.

IntermediateComplete guide
SQL

PostgreSQL

MVCC, data types, powerful SQL, indexes, query tuning and isolation.

IntermediateComplete guide
NoSQL

MongoDB

Documents and collections, CRUD, queries and data modelling.

Beginner20+ tutorials
NoSQL

Cassandra

Replication, tunable consistency, CQL and query-first data modelling.

AdvancedComplete guide
NoSQL

CouchDB

Documents over HTTP, Mango queries, views, replication and Spring Boot.

IntermediateComplete guide
NoSQL

Redis

Data types, persistence, eviction, clustering and Spring Boot caching.

IntermediateComplete guide
Roadmap

Your Java Developer Roadmap

Six stages from your first Java program to designing distributed systems. Each stage builds on the one before, so follow them in order or jump to the one you need.

  1. 01Beginner

    Java Foundations

    Write clean, object-oriented Java and know what each LTS release added.

  2. 02Intermediate

    Problem Solving

    Pick the right data structure and recognise reusable designs.

  3. 03Beginner

    Databases

    Model data, write efficient SQL and know when NoSQL fits better.

  4. 04Intermediate

    Spring Boot

    Build secure, production-ready REST APIs backed by a database.

  5. 05Advanced

    Microservices & Kafka

    Split systems into services that communicate reliably through events.

  6. 06Advanced

    System Design

    Design scalable systems and explain the trade-offs in interviews.

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.

Sandeep, creator of JavaByTechie
About the Author

Hey, I’m Sandeep, Creator of JavaByTechie

Senior Java Engineer & Technical Author

I'm a senior Java engineer with over a decade of experience designing and building large-scale distributed systems with Java, Spring Boot, Microservices, Kafka and other technologies. I’ve worked across banking, fintech, e-commerce and SaaS products, led engineering teams 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.

For suggestions, feedback or collaboration, please get in touch.
contact@javabytechie.com

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