Kotlin runs on the JVM, calls any Java library, and is a first-class language in Spring Boot, with Ktor as its own server framework. This path starts with Kotlin's fundamentals, then adds the SQL, Linux, Git and Docker every backend job assumes. Free, in your browser, with a certificate for each course.
199,718+ codders enrolled across these courses
492 lessons626 challenges2,358 quiz questions
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A path certificate at the end, plus 8 along the wayEach step is an existing Coddy course, and the first step's Start button opens the Kotlin course. Take them in order, or start from the one you are missing: progress is saved per course either way.
val and var, null safety, when, loops, functions and lists. Classes and coroutines are not in the Kotlin course yet, so this step is the language's foundations, not all of it.StartDedicated pageSELECT, WHERE, JOIN, GROUP BY and subqueries, plus indexes and schema design, run against live tables. Kotlin backends reach the database through Spring Data or Exposed, JetBrains' SQL library, and both reward knowing the SQL underneath.StartDedicated pagebuild.gradle.kts, is versioned and reviewed like everything else.StartDedicated pageWrite real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.
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Promotion zoneRead, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.
A variable is a named container that stores a value you can reference later in your program.
In Python, you create one by writing the name, an equals sign, then the value you want to store.
The value can change over time. Reassigning the name simply points it to a new value.
Earn certificates for every course you complete. Add them to your LinkedIn profile and resume to showcase your coding expertise to employers.
Certificate of CompletionPython Fundamentals
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when expressions in place of Java's boilerplate.String?) and makes you handle it with ?. or ?: before it can become a NullPointerException in production. The Kotlin course teaches this early.Yes. It runs on the JVM with the whole Java ecosystem behind it, Spring Boot supports it as a first-class language, and coroutines make asynchronous code read like ordinary sequential code. The trade-offs: fewer backend openings than Java, since Kotlin's biggest market is Android, and most Spring and Hibernate documentation is written for Java, so you will read Java as well.
Java for the widest job market; Kotlin for null safety, less boilerplate and coroutines on the same JVM. The two mix in one codebase, so the choice is less final than it looks: Kotlin services call Java libraries all day, and a Java team can add Kotlin one file at a time. Either way, a Kotlin backend developer ends up reading Java.
Spring Boot for most jobs: it is what enterprise teams already run, and it supports Kotlin fully. Ktor, from JetBrains, is lighter and built around Kotlin's coroutines, a good fit for small services and teams that prefer to assemble only what they need. Neither is taught on this path yet.
val and var, null safety, when, loops, functions and lists. Classes and coroutines are the next things a Kotlin backend developer needs, and they are not in the course yet. Step one is the whole Kotlin course, so a section added to it later appears in this path on its own.At an hour a day, the Kotlin course takes about four weeks, SQL two to three, and Linux, Git and Docker about a month together: two to three months for the foundations on this path. Job-ready usually means adding classes, coroutines and Spring Boot or Ktor on top, plus one real service with a database, which takes a few months more.
Yes. Every course on it is free: the Kotlin lessons, the SQL and terminal exercises, Bugsy's hints and a certificate for each course you finish, each verifiable at its own URL. Kotlin compiles server-side, so there is no JDK or IntelliJ to install.
Yes. Finish every step and you get one free certificate for the whole Backend Developer path. It lists each course you finished on the way, and links each course's own certificate, so anyone can check every skill it names. You can add it to your LinkedIn profile. It is a certificate of completion from Coddy, not an accredited qualification.
