These are some demo api's that are hosted on Render which you can use to test this out.
- C - https://c-compiler-cv4p.onrender.com/compile
- C++ - https://cpp-compiler.onrender.com/compile
- Java - https://java-compiler.onrender.com/compile
- Python3 - https://python-compiler.onrender.com/compile
- Javascript - https://javascript-compiler.onrender.com/compile
- Golang - https://go-compiler-lcrn.onrender.com/compile
- Rust - https://rust-compiler.onrender.com/compile
Thanks to Render.com for the free hosting.s