Learning path

Kotlin Backend Developer Roadmap

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.

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203,556+ codders enrolled across these courses

492 lessons572 challenges2,358 quiz questions

Beginner friendly
AI-assisted coding help
Hands-on interactive lessons
Audio narration on every lesson
Quizzes to test your knowledge
8 free certificates along the path

The Kotlin backend developer roadmap, step by step

5 courses8 sections492 lessons572 challenges2,358 quiz questions

Each 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.

1
Step 1
KotlinDedicated page
Start this stepStartFundamentals and Logic & Flow: 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.Start Dedicated page
3 sections, in order
213 lessons322 challenges826 questions
2
Step 2
SQL and databasesDedicated page
Start this stepStartQueries with SELECT, 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.Start Dedicated page
2 sections, in order
1. Fundamentals72 lessons72 challenges360 questions
2. Beyond the Basics27 lessons28 challenges167 questions
99 lessons100 challenges527 questions
3
Step 3
Linux and the command lineDedicated page
Start this stepStartFiles, permissions, processes, pipes and bash basics. A Kotlin service runs as a JVM process on a Linux server, and that is where you start it, read its logs and find out why it stopped.Start Dedicated page82 lessons68 challenges440 questions
4
Step 4
Git and version controlDedicated page
Start this stepStartCommits, branches, merging, conflicts, remotes and undoing mistakes. In a Kotlin project even the build is code: the Gradle script, often build.gradle.kts, is versioned and reviewed like everything else.Start Dedicated page58 lessons46 challenges370 questions
5
Step 5
Docker and containersDedicated page
Start this stepStartImages, Dockerfiles, volumes and networking. A Ktor or Spring Boot service builds to one runnable JAR, and a container image around it runs the same on your laptop, in CI and in production.Start Dedicated page40 lessons36 challenges195 questions

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Intro to Variables

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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.

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Python Fundamentals

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Why learn backend development in Kotlin on Coddy

Java's ecosystem, less code. Kotlin compiles to JVM bytecode and calls Java libraries directly, so Spring, Hibernate and every JDBC driver are there for it, with type inference, string templates and when expressions in place of Java's boilerplate.
Null safety where backends break. A missing request field or an absent row shows up as a null; Kotlin puts that in the type (String?) and makes you handle it with ?. or ?: before it can become a NullPointerException in production. The Kotlin course teaches this early.
One language from app to API. Android teams moving to the server can keep one language across the app and the backend, and Kotlin Multiplatform lets them share code such as data models and validation between the two.
Graded, in the browser. No IntelliJ and no JDK: every Kotlin lesson ends in a challenge checked by tests, and when yours fails, Bugsy, the AI tutor, reads your code and the compiler error and nudges you toward the fix. Each course ends with a free certificate.

Frequently asked questions about Kotlin backend development

Is Kotlin good for backend development?

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.

Kotlin or Java for backend development?

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 or Ktor for a Kotlin backend?

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.

Does this Kotlin backend path cover classes and coroutines?

Not yet. The Kotlin course has two sections, Fundamentals and Logic & Flow, which cover 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.

How long does it take to become a Kotlin backend developer?

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.

Is this Kotlin backend roadmap free?

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.

Other learning paths

The same courses, arranged for a different role. Progress carries over: a course finished on one path counts on every path that includes it.

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