Where does my C code run?

On a sandboxed third-party execution service, not on induwara.lk's servers. Your code is sent to an isolated compiler environment, run there, and the result is returned. Our server only forwards the request (with strict rate limits and size caps) — it never executes your code, so there's no way for a program to reach our systems.

Is the C compiler free to use, and do I need an account?

Yes, it's completely free and there's no signup. Just write your code and press Run. It's meant as a quick, zero-setup way to compile and test code from any device, including a phone.

Is this good for learning C?

Very — C is the classic first systems language, and this lets you practise pointers, arrays, structs, and standard-library functions with zero setup from any device. Write a program, run it, and read the output or compiler errors instantly.

Do compiler warnings show up?

Compilation errors are shown with line numbers in the output panel. If your program doesn't compile, you'll see GCC's messages so you can fix and re-run — the same feedback loop as a local build.

Which compiler / version is used?

It compiles with a recent GCC using a modern C standard, so the full C standard library (stdio, stdlib, string, math) works.

Are there limits on run time or code size?

Each run has a 30-second limit and a 50 KB code-size cap, and there are per-IP and overall rate limits so the shared compiler stays fast for everyone. For big projects use a local toolchain; this is built for snippets, exercises, and quick tests.

Can I read interactive input (stdin) while it runs?

Interactive input isn't wired into this editor yet — programs run start-to-finish and their output is shown. For exercises that need input, set the values directly as variables in your code. Everything printed to standard output appears in the output panel.

Developer · Runs in your browser

Online C Compiler — write, compile & run C

Compile and run C instantly online, free and no signup. Your code is built with GCC on a sandboxed server — never on ours — so it's safe and works from any device.

By Induwara Ashinsana— Executive Director, Ryzera TechnologiesUpdated May 28, 2026

C · runs on a sandboxed server

Loading editor…

Output

Press Run to execute. Output appears here.

How it works

C compiles to a native executable, which needs a real compiler (GCC) — not possible in a browser. The server compiles your main() with GCC and runs the binary, returning printf output and any errors. The C standard library is fully available.

When you press Run, your C code is sent to a sandboxed execution service that compiles and runs it in an isolated environment, then returns the output. It does notrun on induwara.lk's servers — our site only proxies the request, so your code can never touch our systems, files, or other users. Languages like Cneed a real compiler/runtime, which isn't practical in a browser, so this is the safe way to offer them.

The proxy is strictly bounded: a 30-second execution limit, a 50 KB code cap, and per-IP plus global rate limits that protect the shared compiler. There's no signup and nothing to install — write code, hit Run, read the output.

Frequently asked questions

Sources & references

Compilation + execution happen on Wandbox's isolated servers; induwara.lk only proxies the request with rate limits and caps.

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Found a bug or want another language added?

Email me at [email protected].