CORS Proxy vs Wandbox

CORS Proxy is a small open-source Node.js server (54 GitHub stars) that forwards a POST request's urlToGet body param to the target URL server-side and relays the response back with permissive CORS headers, sidestepping browser CORS errors for GET-able resources. It is a deploy-it-yourself utility, not a hosted service — the README's old Heroku demo link is dead since Heroku retired free dynos in 2022, so it only works once cloned and deployed to your own host.

Wandbox is a free "social compilation service" built by melpon and kikairoya, offering 175 compiler configurations across 35 languages — from mainstream C++, Python, Rust, and Go to niche picks like Lazy K and Pony — including nightly HEAD builds of GCC and Clang. Its REST API needs no key: POST source code, a compiler ID, and options to /api/compile.json (or the /ndjson variant for streamed output) and get back compile/runtime output plus a permanent shareable permalink, while /api/list.json enumerates every compiler and its supported switches. The project was rewritten in 2024–2026 from a legacy Ruby backend to Rust (feline) and Remix (canine), which is why the old kennel2/API.rst docs path 404s — the live API endpoints themselves are unchanged.