Spring Boot
Build production-style Spring Boot backends through hands-on challenges, one concept at a time.
Spring Boot 4.1
Java 25Beans & Dependency Injection
Learn how Spring wires your objects together: registering beans, injecting them without new, choosing between them, and configuring them from properties.
Coffee Shop Order Receipt
Temperature Unit Provider Switcher
Feature Flag Bean Registry
Notification Dispatch Selector
REST Controllers & Endpoints
Learn how Spring turns classes into HTTP endpoints: mapping routes to methods, reading path variables and query parameters, binding request bodies, and returning the right status codes.
Planetarium Show Catalog
Bird Sightings API
Vending Machine Inventory
Comic Book Issue API
Validation and Error Handling
Learn how Spring checks a request before your code runs: applying field constraints, writing your own validation rules, catching every failure in one place, and answering with a consistent error body.
Passport Application Form Validator
Blood Donation Eligibility Check
Global Error Response Standardizer
Pizza Order Constraint Validator
JPA Persistence Basics
Learn how Spring stores your data: mapping classes to tables, saving and loading through repositories, updating a row in place instead of adding a new one, and letting the database enforce its own rules.
Beekeeping Hive Log
Plant Watering Schedule Store
Guitar Lesson Booking Store
Board Game Collection Tracker
Querying and Filtering
Learn how Spring builds queries for you: deriving them from method names, combining filters that may or may not be supplied, writing your own JPQL when derivation runs out, and keeping results in a fixed order.
Farmers Market Vendor Search
Used Textbook Listings Filter
Podcast Episode Browser
Hotel Room Availability Query
DTOs, Mapping and Pagination
Learn how Spring shapes what leaves your API: mapping entities to response objects, keeping internal fields out of the payload, projecting only the columns a view needs, and returning results one page at a time.