Backend Dev Crash Course for Beginners With Spring Boot - Kotlin, JWT Auth, MongoDB (2025)

Learn to build a complete CRUD backend with user authentication and MongoDB integration in this comprehensive 3-hour crash course for beginners. Starting with REST API fundamentals, progress through creating a Spring Boot project with Kotlin, setting up MongoDB Atlas, implementing JWT authentication, and building user registration and login functionality. Follow along as the tutorial covers essential concepts including Spring's Bean mechanism, security configuration, field validation, and proper HTTP status code responses. By the end, create a fully functional secured backend that allows users to register, login, and manage notes in a MongoDB database. The course includes practical demonstrations with complete source code available on GitHub, making it ideal for those new to backend development.

Syllabus

00:00 Prerequisites
1:43 - What even is a REST API?
7:25 - What is a backend framework?
9:55 - What we will build
11:02 - Creating a Spring Boot project
15:20 - Project roundtrip
21:18 - Mongo Atlas setup
33:14 - Saving notes to MongoDB
1:06:00 - Base setup for security config
1:12:55 - Checking notes in Mongo Atlas
1:14:24 - Spring's Bean mechanism
1:17:30 - Deleting notes
1:21:05 - Setting up the user collection
1:30:12 - JWT generation & verification
1:57:27 - User registration & login
2:35:55 - Responding with correct status codes
2:44:57 - Field validation
2:52:47 - Trying it out & fixing last bugs