Online code execution system.
Judge0 CE API is a free Programming API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Details from ce.judge0.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
For upcoming and ongoing competitive coding contests
The Judge0 CE API is provided by Judge0 CE (ce.judge0.com).
Yes. The Judge0 CE API is listed in the Programming category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The Judge0 CE API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Judge0 CE API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Judge0 CE API is served over HTTPS, so it's safe to use in production.