OCaml is a programming language that can feel quite different when you first meet it, but that difference is exactly what makes it interesting for project-based learning. Instead of simply writing code that produces an output, you start thinking more carefully about types, functions, data structures, pattern matching, and how different parts of a program fit together.
As of 2026, the language continues to receive active development, with OCaml 5.5.0 released on June 19, 2026, bringing language improvements, garbage collector enhancements, and around 60 new standard-library functions.
That’s a big reason why this is a good time to start building things with it. This list walks through OCaml project ideas for every stage — whether you’re just getting past the basics or you want something meatier to sink your teeth into. Pick one, open your editor, and just start typing.
Why Should You Build Projects in OCaml?
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Reading about a language only gets you so far — you really start to “get” OCaml once you’re building stuff with it. Here’s why it’s worth the effort:
1. You actually learn the type system by breaking it: OCaml’s compiler is strict, and honestly that’s a good thing. When you build something real, you’ll hit type errors constantly at first — and that’s how it clicks.
2. Pattern matching starts making sense: It sounds abstract until you use it to handle real data in a real project. Then it just feels natural.
3. You get comfortable with functional thinking: No loops, no mutable variables everywhere — projects force you to think in a new way, which is the whole point.
4. You build something you can show off: A project on GitHub says way more than “I know OCaml” on a resume ever could.
5. It’s just more fun than tutorials: Tutorials get boring fast. Projects don’t.
| If you’re into exploring project ideas across different languages, check out our Vue project ideas guide too — same idea, different stack. |
OCaml Project Ideas for Beginners
If you’re just starting out, don’t jump into anything too fancy. These OCaml project ideas are simple enough to finish in a weekend but still teach you real stuff — pattern matching, recursion, basic I/O, that kind of thing. Here are six good ones to kick things off.
1. Simple Calculator
A calculator is the classic “first real project” for a reason — it’s small, but it forces you to deal with parsing input, handling operators, and dealing with edge cases (like dividing by zero). You’ll also get comfortable with basic function structure early on, which makes everything after this a bit easier.
🔗 github.com/ocaml/ocaml-calculator-example
2. To-Do List CLI App
This one’s great because it feels useful right away. You add tasks, mark them done, maybe save them to a file. It’s a nice intro to working with lists and basic state in OCaml — one of those beginner OCaml project ideas that actually feels like a “real” app once it’s done.
🔗github.com/ocaml-community/todo-cli
3. Number Guessing Game
Pick a random number, let the user guess, give hints like “too high” or “too low.” Sounds basic, but it’s a solid way to practice loops (well, recursion in OCaml’s case), conditionals, and random number generation without overthinking it.
🔗github.com/ocaml/number-guess-game
4. Basic Notes Manager
Similar to the to-do app but a bit more flexible — save short notes, list them, delete them. This teaches you file handling and basic data structures, which come up in almost every OCaml project you’ll build later.
🔗github.com/ocaml-community/notes-manager
5. Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin. It’s tiny, but it’s a good excuse to practice writing clean functions and thinking about types properly — which, let’s be honest, is half the point of learning OCaml anyway.
🔗https://github.com/topics/temperature-converter
6. Simple Quiz App
Build a quiz that asks questions, checks answers, and keeps score. It’s a nice step up because you’re combining a few things at once — lists, conditionals, and a bit of user interaction — which is exactly what makes it a solid pick among OCaml project ideas for beginners.
🔗github.com/ocaml-community/quiz-app
Intermediate OCaml Project Ideas
Once the basics feel comfortable, it’s time to push a little harder. These OCaml project ideas involve working with real data, external libraries, and slightly messier problems — the kind of stuff you’ll actually run into once you start building bigger things. Here are six worth trying.
7. JSON Parser
Writing your own JSON parser (or using one) teaches you a ton about recursive data types and pattern matching — two things OCaml is really good at. You’ll deal with nested structures, error handling, and type conversions, which honestly makes this one of the more satisfying OCaml project ideas on this list once it clicks.
🔗github.com/ocaml-community/yojson
8. Web Scraper
Build something that pulls data off a webpage and organizes it. You’ll get hands-on with HTTP requests, HTML parsing, and handling messy, unpredictable data — which is a very different challenge from the tidy exercises you’ve probably done so far.
🔗github.com/aantron/lambdasoup
9. Simple Chat Application
This one’s a jump — you’re now dealing with sockets, basic networking, and handling multiple connections at once. It’s a bit fiddly to get working at first, but it teaches you a lot about how programs talk to each other over a network.
🔗github.com/ocaml-community/chat-app-example
10. Toy Language Interpreter
Build a small interpreter for a made-up mini language — even something as basic as a calculator language with variables. This is genuinely one of the best OCaml project ideas for intermediate learners because OCaml itself was basically built for this kind of work.
🔗github.com/ocaml/ocaml-interpreter-tutorial
11. Library Management System
Track books, users, and checkouts. Sounds boring on paper, but it’s a solid way to practice organizing a bigger codebase, working with modules, and managing state across different parts of a program — skills that matter a lot once projects get bigger.
🔗github.com/ocaml-community/library-system
12. Command-Line Markdown Renderer
Take Markdown text and convert it into HTML. It’s a great mix of string parsing, pattern matching, and recursion, and you end up with something genuinely useful at the end — always a nice bonus.
🔗github.com/ocaml-community/md-to-html
OCaml Project Ideas for Advanced Learners
Alright, this is where things get properly fun. These OCaml project ideas aren’t weekend projects — they’re the kind of thing that’ll take real time, but they’ll also teach you stuff that separates “I know OCaml” from “I actually understand how this language works under the hood.” Here are six to chew on.
13. Static Type Checker
Build a basic type checker for a small language you define. This forces you to really understand how OCaml’s own type inference works, since you’re essentially recreating a simplified version of it. It’s tough, but there’s nothing quite like the feeling of it actually catching a type error correctly.
🔗github.com/ocaml/ocaml (study the compiler’s type-checking source for reference)
14. Concurrent Web Server
Build a web server that handles multiple requests at once using OCaml’s concurrency tools. This is a great excuse to dig into Lwt or the newer effect handlers in OCaml 5, and honestly, once you get concurrency working properly, it feels like a real milestone.
15. Blockchain Simulation
Build a simplified blockchain — blocks, hashing, a basic consensus mechanism. It won’t be production-ready obviously, but it’s a genuinely great way to practice working with immutable data structures, which is exactly what OCaml is built for. Worth checking out how real projects like Tezos do it too.
16. Distributed Key-Value Store
Build (or study) a simple database that syncs data across nodes. This is a jump in complexity, but it’s one of the more rewarding OCaml project ideas if you’re into systems programming — Irmin is a real-world example that does exactly this and is worth digging into.
17. Custom Programming Language with Parser Generator
Take your toy interpreter from earlier and level it up using a proper parser generator like Menhir. You’ll write your own grammar, generate a real parser, and build out a language that actually feels legit — arguably the most “OCaml” project on this whole list.
18. Compile-to-JavaScript Tool
Try building a small tool (or explore an existing one) that compiles OCaml code into JavaScript so it runs in the browser. It’s a deep dive into compilers and how different languages talk to each other, and js_of_ocaml is a great real-world project to learn from.
🔗github.com/ocsigen/js_of_ocaml
Tips for Choosing the Right OCaml Project Idea
With this many options, it’s easy to just pick something random and get stuck halfway through. Here’s how to actually choose well:
1. Be honest about your current level: It’s tempting to jump straight into something advanced because it looks cool, but if you’re still shaky on pattern matching, start smaller. You’ll learn faster by finishing something than by abandoning a project that was too much too soon.
2. Pick one thing you want to get better at: Don’t try to learn recursion, modules, and concurrency all in one project — you’ll just end up confused. Pick a project that leans into one or two skills and let the rest come naturally.
3. Go with something you’d actually use: A to-do app or notes manager might sound boring, but you’ll finish it faster because you actually care about the outcome. Motivation matters more than people give it credit for.
4. Don’t skip the “boring” beginner projects: Even if you’ve coded in other languages before, OCaml’s way of thinking is different enough that the simple stuff still teaches you something. Ego gets in the way here more than people admit.
5. Set a rough time limit: Give yourself a weekend, or a week — whatever feels reasonable. Without some kind of deadline, projects have a sneaky way of sitting half-finished forever.
6. Use Git from day one, even for tiny projects: It’s a small habit that pays off fast, especially once you start looking back at older code and wondering what past-you was thinking.
Where to Find More OCaml Project Ideas
Run out of ideas from this list, or just want to keep exploring? Here are some solid places to look:
GitHub’s “OCaml” topic page: Just search OCaml on GitHub and filter by stars or recently updated — you’ll find tons of real projects people are actively building, which is honestly more useful than any list (including this one).
Exercism’s OCaml track: It’s not exactly “project” based, but the exercises are well thought out and get progressively harder, so it’s a good way to fill gaps between projects.
Rosetta Code: Great for seeing how the same small problem gets solved in OCaml versus other languages — weirdly useful for understanding what makes OCaml different.
OCaml Discourse and Reddit: People post their own projects all the time, and you’ll often stumble on ideas you never would’ve thought of yourself.
Advent of Code: Not OCaml-specific, but doing it in OCaml each December is a genuinely fun way to practice.
Final Thoughts
That’s a solid stack of OCaml project ideas to keep you busy for a while — whether you’re just past “hello world” or you’re ready to build something that actually pushes you. The truth is, you don’t need to work through every single one in order. Pick whatever sounds fun or useful to you right now, and just start.
The biggest mistake people make isn’t picking the “wrong” project — it’s overthinking which one to start with and never actually starting. So grab one of these OCaml project ideas, open your editor, and let yourself get stuck a few times. That’s honestly where most of the learning happens anyway.
FAQs
1. Is OCaml good for beginners?
Yeah, honestly it is. It’s strict and makes you think differently at first, but that strictness actually helps you catch mistakes early and learn faster.
2. What can you build with OCaml?
Pretty much anything — calculators, web scrapers, compilers, even blockchain stuff. It’s especially strong for anything involving parsing, type safety, or complex logic.
3. How many OCaml projects should I build before I feel confident?
There’s no magic number, but somewhere around 5-6 varied projects usually gets you comfortable enough to tackle bigger, messier ideas on your own.
