In this guide, you will find the best free online courses and resources to learn OCaml,  a general-purpose, statically-typed programming language that is widely used for building robust, expressive, and performant applications.

Though OCaml puts the functional style first, it supports other paradigms like object-oriented and imperative programming, giving developers a high degree of flexibility. Along with its robust type system which guarantees safety and reliability, OCaml is a popular choice among large organizations such as Facebook, Microsoft, Bloomberg, and Jane Street. OCaml’s versatile nature enables developers to use it for a wide range of tasks, from writing compilers and developing trading systems, to creating domain-specific languages and web-crawling applications.

If you’re interested in learning a language that combines efficiency, expressiveness, and practicality in a way unmatched by any other language, read on more to find my top picks for the best OCaml course.

But if you’re in a hurry, here are my top picks. Click on one to skip to the course details:

Course	Workload	In Brief
1. OCaml Programming: Correct + Efficient + Beautiful  (Cornell University)	N/A	Best free university-level course with videos, textbook, and exercises
2. Introduction to Functional Programming in OCaml (Université Paris Diderot)	7 hours	Best free university-level video course
3. Programming with OCaml (Anthony Narlock)	3–4 hours long	Best free short video course
4. OCaml By Example (O(1) Labs)	N/A	Best free article-based course
5. OCaml Workshop (Jane Street)	N/A	Best free hands-on exercise and project-based course
6. Learn OCaml (OCaml Software Foundation)	N/A	Best free short exercise-based course
7. OCaml (Exercism)	N/A	Best free exercise-based course with free mentoring

What is OCaml?

OCaml is a general-purpose, statically-typed programming language with an emphasis on expressiveness and safety. It was designed in 1996 by Xavier Leroy and his team at INRIA in France as an extension of the Meta Language Caml dialect. Although Caml had a powerful type system and functional programming capabilities, it was only ever used in academia. However, by incorporating features such as object-oriented programming while retaining the correctness and conciseness of its predecessor, OCaml became a suitable language for building practical, real-world applications (which is what the O in OCaml formerly stood for Objective, if you were wondering).

OCaml’s strong type system, inherited from its predecessors, helps ensure code is safe and correct by catching errors at compile-time, while maintaining the flexibility of untyped languages by performing type inference. Not only that, OCaml’s algebraic data types allows for powerful pattern-matching capabilities, making it easy to match, extract and manipulate data in a concise and expressive way.

Many of OCaml’s features encourage programming in the functional style, such as preferring recursion and higher-order functions over traditional loops and preferring immutable data structures over mutable ones. However, it acknowledges that certain tasks  such as working with files and writing in-place algorithms can be difficult to accomplish using only functional methods. As a result, OCaml offers support for multiple programming paradigms like imperative and object-oriented programming, giving developers flexibility to choose the best paradigm for their problem.

OCaml is also known for performance and ability to easily integrate with other languages, such as C and JavaScript, making it a great choice for building multi-language systems.

As for its applications, OCaml is widely used in academia and research institutions, with many universities like Cornell and Princeton including it in their curriculum to teach functional programming. And although OCaml is relatively niche compared to other languages, it has been used in several large-scale industry projects by companies such as Facebook for compilers and static analysis, Jane Street for guaranteeing the correctness of their internal trading systems, Coq for checking mathematical theorems, and Bloomberg for advanced financial derivatives risk management application.

Best Courses Guides Methodology

I built this ranking following the now tried-and-tested methodology used in previous Best Courses Guides (you can find them all here). It involves a three-step process:

1. Research: I started by leveraging Class Central’s database with 100K online courses and 200K+ reviews. Then, I made a preliminary selection of OCaml courses by rating, reviews, and bookmarks.
2. Evaluate: I read through reviews on Class Central, Reddit, and course providers to understand what other learners thought about each course and combined it with my own experience as a learner.
3. Select: Well-made courses were picked if they presented valuable and engaging content and they have to fit in a set of criteria and be ranked accordingly: comprehensive curriculum, affordability, release date, ratings and enrollments.

Course Ranking Statistics

Here are some aggregate stats about the ranking:

• All of the courses in this ranking are free or free-to-audit.
• All of the courses are suitable for beginners to OCaml. Unfortunately, none of the courses are geared towards complete beginners to programming.
• Two of the courses are from universities while the rest are from independent providers.

Without further ado, let’s go through the top picks.

1. OCaml Programming: Correct + Efficient + Beautiful  (Cornell University)

The number one OCaml course in this ranking is OCaml Programming: Correct + Efficient + Beautiful from Cornell University.

This free course is my top pick because it is both a textbook and a bite-sized video series. This means that you’ll learn not only through comprehensive written explanations and examples, but also through visual demonstrations and coding exercises.

The course covers a wide range of topics related to OCaml, including functional programming, correctness and efficiency, data structures, and best software engineering practices.

Prior knowledge programming in some mainstream imperative language (Java and Python preferred) and first-semester standard discrete mathematics is assumed prior to taking this course.

What You’ll Learn

You’ll start straight away by diving into the basics of OCaml, starting with basic syntax like writing expressions and functions. You’ll quickly familiarize yourself with the functional style of programming through extensive use of OCaml’s REPL.

As you become more comfortable with the language’s distinctive syntax, you’ll find yourself appreciating its underlying principles that help developers write concise yet expressive, correct yet efficient code. For example, OCaml is awesome for writing compilers thanks to functional programming concepts such as parametric polymorphism, algebraic data types, higher-order programming, pattern matching. Hence, you’ll study all of these in-depth, along software engineering best practices such as error handling, testing, and documentation.

Not only that, data structures will also be covered in the course, from the ones available in the standard library to more complicated data structures that you’ll implement on your own using both imperative and functional programming. You’ll be able to analyze the efficiency of data structures using amortized analysis and choose the one that suits your use case.

Remember that I mentioned OCaml is great for writing compilers? Well, the final part of this course demystifies compilers enough for you to design and implement some small, special-purpose domain-specific languages (DSLs).

How You’ll Learn

This course consists of 9 chapters. You’ll learn by reading through the chapters and watching the videos. At the end of each chapter except the first, you’ll find exercises for you to practice what you’ve learned. Additionally, the course has a feature called collaborative annotations that allows you to highlight and make private notes that you can share with others.

Institution	Cornell University
Instructor	Michael R. Clarkson
Level	Beginner
Workload	N/A
Certificate	None

Fun Facts

• Michael R. Clarkson is a professor at Cornell University. These series of videos and the textbook are materials for the CS 3110 Data Structures and Functional Programming using the OCaml programming language. Due to overwhelming positive feedback, Michael made the videos publicly available for anyone who wants to learn about OCaml, functional programming, and becoming a better programmer.

If you’re interested in this course, you can find more information about the course and how to enroll here.

2. Introduction to Functional Programming in OCaml (Université Paris Diderot)

My second pick for the best OCaml course is Introduction to Functional Programming in OCaml offered by Université de Paris.

This MOOC focuses on teaching the principles of functional programming using the OCaml programming language by emphasizing the use of functions as first-class values to create and manage complex data structures. The course will begin by showing the use of OCaml as a functional programming language alone, and by the end, it’ll demonstrate how OCaml can be utilized as a multi-paradigm language, combining functional and imperative programming styles to get the best of both worlds.

To follow this course, you should already have some basic knowledge of writing simple computer programs in a programming language.

What You’ll Learn

You’ll begin the course with an overview of the language, starting with its robust type system. OCaml is statically-typed language, but thanks to its flexible type inference you’ll find yourself working with the type-checker rather than against it, and even create your own types. Combined with immutable data structures, such as tuples, records, and trees, you’ll see how they can be used effectively in your programs.

As a functional-first programming language, OCaml emphasizes the concepts of functional programming (FP), including the use of recursion over loops and the treatment of functions as first-class citizens. You’ll gain hands-on experience with key FP concepts such as partial function application, map and fold operations, and more.

By now, you’ve probably gotten a good understanding of how functional programming differs from imperative programming. Imperative programming is useful in some cases though, so you’ll explore OCaml’s imperative constructs such as modules, input/output, and exceptions.

How You’ll Learn

This course is 6 weeks long, with the total video watch time adding up to 7 hours. You’ll learn by watching the lecture videos and following along with the examples provided by the instructors.

Institution	Université de Paris
Provider	YouTube
Instructors	Roberto Di Cosmo, Yann Regis-Gianas, and Ralf Treinen
Level	Beginner
Workload	7 hours
Enrollments	1.5K
Certificate	None

Fun Facts

• Roberto Di Cosmo is professor of computer science at University Paris Diderot, director of Irill, currently on leave at INRIA. His research interests include functional and parallel programming, type systems, logic, rewriting, and the static analysis of large software collections.
• Yann Régis-Gianas teaches computer science at Université Paris-Diderot. His research at the PPS laboratory focuses on the theory and the design of programming languages. He did his PhD in the INRIA team that develops OCaml and is now in the development team of the Coq proof assistant.
• Ralf Treinen is professor of computer science at University Paris Diderot. Symbolic constraint solving, verification and application of formal methods to the quality assurance of software components are among his current research interests. He is also a member of Irill.

If you’re interested in this course, you can find more information about the course and how to enroll here.

3. Programming with OCaml (Anthony Narlock)

Programming with OCaml teaches the basics of programming in OCaml, especially how it differs from other traditional programming languages.

No prior knowledge of OCaml is required to take this course. This is the first installment of Narlock OCaml programming tutorial series, soon there will be more content available.

Channel	narlock
Provider	YouTube
Instructor	Anthony Narlock
Level	Beginner
Workload	1 hour long
Views	517
Likes	26
Certificate	None

Fun Facts

• Anthony Narlock is an experienced software developer with programming experience in Java, Python, and C++. He has a YouTube channel where he posts study with me, vlogs, educational tutorials, and software update videos.

If you’re interested in this course, you can find more information about the course and how to enroll here.

4. OCaml By Example (O(1) Labs)

Learn the OCaml language by following a series of examples in the Ocaml By Example course!

No prior experience of OCaml is required to take this course.

What You’ll Learn

You’ll start this course with an overview of the basic language constructs such as values, functions, pattern matching, tuples, variants, lists, sets, arrays, and records. Although most of the concepts you’ll learn relate to functional programming, you’ll also understand how to program imperatively in OCaml as it is a multi-paradigm language.

Next, you’ll study data structures and algorithms, such as recursion, hash tables, and their implementation in the OCaml language. You’ll also understand the different ways to organize your code, such as modules and packages with the Dune build tool. Error handling and interacting with the file system are some other concepts you’ll also cover.

Finally, you’ll learn the more advanced parts of Ocaml, such as macros, and explore OCaml’s vast library collection, including interoperating with other programming languages such as C, JavaScript, and Rust.

How You’ll Learn

This course is made up of four chapters. You’ll learn by reading through the different articles along with the code examples provided.

Institution	O(1) Labs
Provider	GitHub
Level	Beginner
Workload	N/A
Stars	30
Certificate	None

Fun Facts

• This page was inspired by Go by Example.

If you’re interested in this course, you can find more information about the course and how to enroll here.

5. OCaml Workshop (Jane Street)

Jane Street’s OCaml Workshop aims to help people start developing in OCaml through small hands-on exercises and bigger, more complex projects like arcade games.

To take this workshop, you should have some experience with OCaml.

What You’ll Learn

After you get familiarized with OCaml’s build process and tools, you’ll complete twenty one exercises teaching you OCaml features such as pattern matching, higher order functions, options, and anonymous functions.

Once you get that covered, you’ll begin developing simplified clones of three arcade games: Snake, Lumines, and Frogger. Snake and Lumines both run on your computer, whereas Frogger runs on your web browser. Afterward, you can choose between several more advanced projects, such as writing a IRC bot, implementing command-line fuzzy finder, or improving Frogger.

How You’ll Learn

Two types of exercises are given: small coding exercises and large projects. Small coding exercises test your understanding of different programming aspects of the OCaml language, whereas the larger projects provide the opportunity to apply your knowledge and skills to more complex, real-world problems. You’ll need to pass the `expect` tests in order to fully complete the exercises.

The course also provides a few paths you can take after completing the exercises, but these come without `expect` tests.

Institution	Jane Street
Provider	OCaml
Level	Beginner
Workload	N/A
Stars	390
Certificate	None

Fun Facts

• Jane Street is a quantitative trading firm. It is a significant user of OCaml, which is used in several areas of its technology stack, including trading systems, risk management, and data processing.
• This workshop was part of the The OCaml Users and Developers Workshop that brings together the OCaml community, including users of OCaml in industry, academia, hobbyists, and the free software community.

If you’re interested in this course, you can find more information about the course and how to enroll here.

6. Learn OCaml (OCaml Software Foundation)

OCaml Software Foundation’s Learn OCaml site provides a variety of coding challenges for you to practice OCaml programming taken from Université de Paris OCaml courses.

Experience with OCaml is recommended to do the exercises.

What You’ll Learn

The difficulty of the exercises ranges from one star (very easy) to four stars (very hard).

Some of the easier exercises include searching for strings in arrays, balancing binary trees, and using first-class functions.

Meanwhile, the more difficult exercises include implementing algorithms such as merge sort and huffman compression, displaying a filesystem hierarchy, and developing a mini database.

How You’ll Learn

You’ll write and execute code directly in the browser’s coding environment. After each exercise, you’ll receive a grade based on how efficient your code is.

Organization	OCaml Software Foundation
Website	ocaml-sf.org
Level	All levels
Workload	N/A
Certificate	None

Fun Facts

• The OCaml Software Foundation is a non-profit foundation whose mission is to promote, protect, and advance the OCaml programming language and its ecosystem, and to support and facilitate the growth of a diverse and international community of OCaml users.

If you’re interested in this course, you can find more information about the course and how to enroll here.

7. OCaml (Exercism)

Exercism is an online coding platform that offers a variety of programming exercises and challenges that are suitable for all skill levels. It’s a great way to practice and improve your OCaml coding skills for free.

What makes Exercism stand out from other similar exercise providers is that it offers a free mentoring service. If you ever get stuck on an exercise or want to improve your code, you can request feedback from experienced OCaml programmers.

What You’ll Learn

Exercism offers exercises of varying difficulty levels, including easy, medium, and hard.

Examples of easy exercises include reporting leap years, calculating ages of people in a planet’s solar years, and determining if a sentence is a pangram.

Medium exercises include tasks such as counting the number of rectangles in an ASCII diagram, scoring a bowling game, and adding numbers to a minesweeper board.

For those looking for more of a challenge, there are also hard exercises available, such as calculating the date of meetups, implementing logic of hangman game using functional reactive programming, and creating a zipper for a binary tree.

How You’ll Learn

This course is self-paced, so you can take all the time you need to complete the 40+ hands-on programming exercises. Each exercise comes with automatic feedback of your code as well as personal mentoring to help you understand your code’s strengths and flaws.

Provider	Exercism
Level	All levels
Workload	N/A
Enrollments	3K
Certificate	None

Fun Facts

• Exercism provides exercises on 50+ programming languages like Python, Kotlin, F#, and even WebAssembly.
• Their mission is to help everyone get really good at programming, regardless of their background, share the love of programming, and help people upskill as part of their upward social mobility.
• Around 40 people have contributed towards the OCaml syllabus and exercises, with over 60 mentors available at the time of writing.

If you’re interested in this course, you can find more information about the course and how to enroll here.