C Code Checker
Find buffer overflows and common C mistakes: gets, strcpy, printf format bugs, unchecked malloc and assignment in if. Free and private: runs in your browser.
Paste C code to catch the classic security and correctness bugs before they reach a compiler warning or a CVE.
Runs entirely in your browser. Nothing you paste is uploaded or stored.
Use cases
- Check a function before opening a pull request.
- Explain a review comment with numbers instead of opinions.
- Find the riskiest code to refactor first.
Frequently asked questions
Why is gets() dangerous?
gets() cannot limit how much it reads, so any long input overflows the buffer. It was removed from C11; use fgets() with the buffer size.
Is the C Code Checker free?
Yes. It is free with no sign-up, and it runs entirely in your browser, so your input is never uploaded or stored.
How accurate is a browser-based code check?
It uses fast heuristics on the snippet you paste, so it is great for quick feedback. For whole repositories, cross-file analysis and history, run a full CodeInspector scan.
Related tools
Checking one snippet is a start. Scan your whole repository for free with CodeInspector.