Which compiler does this use?

GCC, running server-side, so warnings and errors match a normal local build.

Can I use scanf and read input?

Yes. Standard input is supported, so programs reading from stdin work as expected.

Can I compile multiple files?

No. The playground compiles a single source file at a time.

main.c

Input

Output

Online C Playground

Runs on GCC 9.2.0 · Free · No signup required

A free online C playground and compiler for backend engineers. Write C, compile it with GCC, and run it in your browser — no toolchain install, no makefile, no signup. C is where a lot of systems and backend fundamentals live, and the compile-run loop is exactly what you want to shorten while learning it. Use the playground to check pointer arithmetic before you trust it, see what a struct actually contains, test a string function against an edge case, or work through data structure exercises without setting up a local environment. Compilation happens server-side against real GCC, so warnings and errors match what you would get from your own terminal. Standard input is supported for programs that read with scanf or fgets. If you are studying data structures and algorithms for backend interviews, the playground pairs with our DSA course and challenge arena.

C Playground — Frequently Asked Questions

Which compiler does this use?: GCC, running server-side, so warnings and errors match a normal local build.
Can I use scanf and read input?: Yes. Standard input is supported, so programs reading from stdin work as expected.
Can I compile multiple files?: No. The playground compiles a single source file at a time.

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