ProxyForge
Free auto-updating list of live-tested proxies (HTTP/HTTPS/SOCKS4/SOCKS5), refreshed every 6 h
Rotating Proxy API that produces a working proxy on every request.
ProxyKingdom API is a free Development API that requires apiKey authentication, is served over HTTPS and supports CORS, so it can be called from the browser.

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.
Free auto-updating list of live-tested proxies (HTTP/HTTPS/SOCKS4/SOCKS5), refreshed every 6 h
QR codes and barcodes (Code 128, EAN-13, Data Matrix, PDF417 + more). SVG or PNG output
Yes. The ProxyKingdom API is listed in the Development 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 ProxyKingdom API uses apiKey authentication, so you need to register for credentials before making requests.
Yes. The ProxyKingdom API supports CORS, so front-end JavaScript can call it directly.
Yes. The ProxyKingdom API is served over HTTPS, so it's safe to use in production.