Shipment and Address information.
UPS API is a free Tracking API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Track the health of UPS APIs and stay up to date on issues such as network or system outages, scheduled maintenance, and resolved issues.
Details from ups.com.

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An API to query Brazilian ZIP codes and orders easily, quickly and free
The UPS API is provided by UPS (ups.com). Track the health of UPS APIs and stay up to date on issues such as network or system outages, scheduled maintenance, and resolved issues.
Yes. The UPS 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.
Yes. The UPS API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the UPS API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The UPS API is served over HTTPS, so it's safe to use in production.