An API to query Brazilian ZIP codes and orders easily, quickly and free.
Postmon API is a free Tracking API that requires no API key, is only available over HTTP and has unconfirmed CORS support.
Details from postmon.com.br.

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.
Automatically place subids in affiliate links to attribute affiliate conversions to click data
The Postmon API is provided by Postmon (postmon.com.br).
Yes. The Postmon API is listed in the Tracking 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.
No. The Postmon API requires no authentication, so you can start making requests without signing up.
CORS support for the Postmon API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
No. The Postmon API is only available over plain HTTP, which browsers block on HTTPS sites. Call it from a server instead.