Write, compile and run C programs directly in your browser — free, fast, and with no signup or download required. Type your code below, add input if your program needs it, and click Run to see the result in seconds.
Your C code is compiled and executed in seconds, right from the browser.
Skip setting up GCC or an IDE. Everything runs on our servers, not your device.
Pass values to scanf() and other input functions using the dedicated input box.
A proper code editor with line numbers and C syntax highlighting, not a plain text box.
Save your program as a .c file to your device in a single click.
Write and test C programs from your phone or tablet, not just a desktop.
A C compiler is a program that translates human-readable C source code into machine code — the low-level instructions a processor can actually execute. When you write a C program, the compiler reads it line by line, checks it for syntax errors, and converts it into an executable file. This tool uses GCC (the GNU Compiler Collection), one of the most widely used and well-tested C compilers in the world, so the behaviour you see here closely matches what you would get on a local Linux, Windows, or macOS setup with GCC installed.
Compiling is different from interpreting. An interpreter, like the one Python uses, reads and executes code line by line at runtime. A compiler instead does its work upfront: it builds a complete executable before the program ever runs. This is one reason compiled languages like C are typically faster than interpreted ones — the translation work is already done by the time the program starts. If you want a deeper comparison, see our article on compiler vs interpreter.
C is one of the oldest and most influential programming languages still in active use today. It sits close to the hardware, giving you direct control over memory through pointers, while still being far more readable than assembly language. Understanding C makes it easier to pick up other languages later, because concepts like variables, loops, functions, and memory management in C form the foundation that languages like C++, Java, and even Python build on.
C is also the language most computer science courses start with, largely because it forces you to understand what's actually happening under the hood — how memory is allocated, how data types are stored, and how a program is structured from the ground up. If you're new to the language, our C programming examples for beginners article is a good next step after trying the compiler above.
Not everyone needs a full local development setup just to test a few lines of code. An online C compiler like this one is useful when you want to:
Follow these steps to write, compile, and run your first C program online.
Use the editor panel on the left. A starter "Hello, World!" program is already loaded so you can try running it right away.
If your code uses scanf() or reads from standard input, type each value on its own line in the Input box.
Your program is sent to the compiler, built with GCC, and executed. This usually takes a few seconds.
Program output appears in the Output panel. If there's a compile error, the compiler's error message is shown there instead.
Use the toolbar buttons to copy your code, download it as a .c file, or reset the editor to start a new program.
Yes. This C program compiler is 100% free to use, with no signup, no download, and no usage limits for normal, fair use.
No. The compiler runs entirely in your browser and sends your code to a server for compilation, so you don't need to install GCC or any C compiler on your computer.
Yes. Use the Input (stdin) box next to the editor to type any values your program reads with scanf or similar functions, before clicking Run.
Yes. The editor and output panels resize automatically so you can write and run C code from a phone or tablet browser.
Code is compiled using GCC, so most standard C programs written for C89, C99, or C11 will run correctly.
A clear breakdown of how compiled and interpreted languages actually work, with C and Python as examples.
Simple, well-explained C programs to practice — from "Hello, World!" to sorting and pattern printing.
The most frequent GCC errors and warnings beginners run into, explained in plain English.
A practical guide to int, float, char, double, and how much memory each one actually uses.
How GCC compares to Clang, MSVC, and Turbo C, and which one you should actually use.