Frequently Asked Questions
Quick answers to the most common questions about My Compiler.
How does the compiler work?
Your code runs in a secure sandbox on our execution server (Judge0). It is compiled or interpreted, and the output, execution time and memory usage come back to the editor within seconds.
Which programming languages are supported?
C, C++, C#, Java, Python, JavaScript, TypeScript, Go, Rust, PHP, Ruby, Kotlin, Swift, Scala, R, Perl, Lua, Bash and SQL, plus HTML, CSS, JSON, XML and Markdown previews.
Is My Compiler free?
Yes. All features are free and the service is supported by advertising.
Do I need to log in?
No. You can write and run code without an account. An account is only needed to save your code.
Is my code saved?
Not automatically. The editor resets when you refresh the page. If you log in and press Save, the code is stored in your account.
What is Judge0?
Judge0 is an open-source code execution system. It runs programs in isolated sandboxes with time and memory limits and returns the result.
How does SQL work?
SQL runs in your browser on SQLite compiled to WebAssembly (sql.js). Each run starts with an empty database, and every SELECT is shown as a table. Nothing is stored.
How do I give my program input?
In Python, C and C++, the program pauses where it asks for input and you type the answer in the output, like a terminal. In other languages, a box opens before the run where you enter one value per line.
Can I upload files?
You can upload a source file with the Upload button to load it into the editor. Your program cannot read uploaded files while running.
Can I download my code?
Yes. Download saves the editor content as a file with the right extension, for example main.py. Copy puts it on your clipboard.
Can I share my code?
There are no share links yet. For now, copy or download your code and send it. Link sharing may be added later.
Does it work on mobile?
Yes. The site is responsive and works on phones and tablets. Larger screens give you a more comfortable editor and the language sidebar.
What are the limits?
Each run has a short time limit and limited memory. Code can be up to 100,000 characters and input up to 20,000 characters. Long-running or heavy programs will be stopped.
Can I use external libraries or the internet?
No. The sandbox has no network access and only the standard library of each language is available.
How is security ensured?
Code runs in isolated sandboxes without access to our systems. Saved code is protected by row-level security, so only you can read it, and connections use HTTPS.
Why are ads shown?
Ads pay for servers and code execution, which lets us keep My Compiler free. See our Privacy Policy for how ads and cookies work.
Is there a premium plan?
Not at the moment. If we introduce paid plans, the free version will stay available and we will announce changes on the site.
Why do I see an error or “Time Limit Exceeded”?
Check the error message first: it shows the line with the problem. “Time Limit Exceeded” means the program ran too long, often because of an endless loop or because it is waiting for input that wasn't provided.
How do I delete my data?
Email us from the address you registered with and we will delete your account and all saved code within 30 days.
How can I contact you or report a bug?
Email contact@mycompiler.online. Please include your browser, the language and the code that caused the problem.