Crystal Online Compiler / Interpreter
Write, compile, and run Crystal code online directly from your browser with our free Online Crystal Compiler / Interpreter. Experiment with Crystal’s expressive, Ruby-like syntax and statically compiled programming model without installing the Crystal compiler, LLVM, or configuring a local development environment.
How to Use This Crystal Compiler
- Write or paste your Crystal code
Enter your program in the Code Editor. You can test variables, methods, arrays, hashes, classes, structs, loops, conditions, and other Crystal features supported by the execution environment. - Click the Run button
Select Run to compile and execute your Crystal code. If your program contains a syntax, type, compilation, or runtime error, review the returned feedback, correct the relevant code, and run it again. - Check the Output screen
Your program result and compiler feedback appear in the Output panel. Use the available controls to copy, download, or delete the output before testing another Crystal program.
Key Features
- Free Online Crystal Compiler: Write and execute Crystal programs directly from a modern web browser.
- Zero Installation: No need to install Crystal, LLVM, or configure a local compiler toolchain for supported programs.
- Instant Execution: Click Run and quickly view program output or compiler feedback.
- Ruby-Like Syntax: Work with a clean and expressive syntax that can feel familiar to Ruby developers.
- Static Type Checking: Test Crystal code with its compile-time type inference and static type system.
- Compiled Performance: Practice code written for Crystal’s native compiled programming model.
- Dark and Light Mode: Switch the Code Editor theme for comfortable coding in different lighting conditions.
- Output Controls: Copy, download, or clear generated output directly from the Output panel.
1. How is Crystal different from Ruby in this online compiler?
Crystal’s syntax is heavily inspired by Ruby, so many basic expressions can look familiar. However, Crystal is a statically typed, compiled language, while Ruby is typically dynamically typed and interpreted.
For example, this Crystal code looks very similar to Ruby:
Despite the familiar syntax, not all Ruby code or Ruby gems will work in Crystal because the languages have different runtimes, type systems, libraries, and compatibility rules.
2. How do I print output in Crystal using puts?
Crystal provides puts for printing text or values followed by a newline.
You can also use string interpolation:
Enter the code in the Code Editor, click Run, and view the result in the Output screen.
3. Do I need to install Crystal or LLVM on my computer?
No. You can use this Online Crystal Compiler / Interpreter directly from your browser without installing the Crystal compiler or LLVM locally for supported programs.
A local Crystal development environment may still be preferable for larger projects, dependency management with Shards, native libraries, debugging, or applications requiring unrestricted filesystem and operating-system access.
4. Can I use classes, arrays, and methods in this Crystal compiler?
Yes. These are standard Crystal language features and can be tested in supported programs.